diff --git a/alsa-capabilities b/alsa-capabilities
index d265a3c..3b044dc 100755
--- a/alsa-capabilities
+++ b/alsa-capabilities
@@ -34,7 +34,7 @@
 LANG=C
 
 APP_NAME_AC="alsa-capabilities"
-APP_VERSION="0.5"
+APP_VERSION="0.6"
 
 ## set DEBUG to a non empty value to display internal program flow to
 ## stderr
@@ -384,51 +384,113 @@ function fetch_alsa_outputinterfaces() {
 	    ## construct the path to the hwparams file
 	    alsa_if_hwparamsfile="/proc/asound/card${alsa_dev_nr}/pcm${alsa_if_nr}p/sub0/hw_params"
 	    alsa_if_statusfile="/proc/asound/card${alsa_dev_nr}/pcm${alsa_if_nr}p/sub0/status"
-	    ## check if the chardev exists
-	    if [[ ! -c "${alsa_if_chardev}" ]]; then 
-		[[ ! -z ${DEBUG} ]] && \
-		    debug "alsa_if_chardev \`${alsa_if_chardev}' is not a chardev."
-		alsa_if_chardev="${alsa_if_chardev} (${MSG_ERROR_CHARDEV_NOT_ACCESSIBLE})"
+	    ## before determining whether this is a usb device, assume
+	    ## the monitor file is the hwparams file
+	    alsa_if_monitorfile="${alsa_if_hwparamsfile}"
+	    ## assume stream file for the interface (ie
+	    ## `/proc/asound/cardX/streamY') to determine whether
+	    ## the interface is a uac device, and if so, which class it is
+	    alsa_if_streamfile="/proc/asound/card${alsa_dev_nr}/stream${alsa_if_nr}"	    
+	    ## keep track of status of interface
+	    alsa_if_closed=0
+	    ## assume no uac device
+	    alsa_if_uacclass="${MSG_PROP_NOTAVAILABLE}"
+
+	    if [[ ! -z ${TESTFILE} ]]; then
+		## device is not real
 		alsa_if_formats+=("(${MSG_ERROR_CHARDEV_NOFORMATS})")
-		alsa_if_monitorfile="${alsa_if_hwparamsfile} (error: not accessible)"
-	    else
-		[[ ! -z ${DEBUG} ]] && \
-		    debug "alsa_if_chardev \`${alsa_if_chardev}' is a valid chardev."
-		if [[ "$(< ${alsa_if_statusfile})" != "closed" ]]; then
-		    ## device is being used, get the locking pid
-		    res="$(get_locking_process "${alsa_if_chardev}")"
-		    if [[ $? -ne 0 ]]; then
-			## can't determine
-			[[ ! -z ${DEBUG} ]] && \
-			    debug "${FUNCNAME}: get_locking_process returned error: \`${res}'"
-			
-			alsa_if_chardev="${alsa_if_chardev} (${MSG_ERROR_LOCKED_UNKNOWN}"
-			alsa_if_formats+=("(${MSG_ERROR_DEVICE_LOCKED})")
-		    else
-			if [[ ! -z "${res}" ]]; then
-			    alsa_if_chardev="${alsa_if_chardev} ${res}"
+		alsa_if_uacclass_nr="?"
+		alsa_if_uacclass_label="${MSG_PROP_NOTAVAILABLE}"
+	    else 
+		## check if the hwparams file exists
+		if [[ ! -f "${alsa_if_hwparamsfile}" ]]; then
+		    alsa_if_hwparamsfile="${alsa_if_hwparamsfile} (error: not accessible)"
+		fi
+		## check if the chardev exists
+		if [[ ! -c "${alsa_if_chardev}" ]]; then 
+		    [[ ! -z ${DEBUG} ]] && \
+			debug "alsa_if_chardev \`${alsa_if_chardev}' is not a chardev."
+		    alsa_if_chardev="${alsa_if_chardev} (${MSG_ERROR_NOT_CHARDEV})"
+		else
+		    [[ ! -z ${DEBUG} ]] && \
+			debug "alsa_if_chardev \`${alsa_if_chardev}' is a valid chardev."
+		    if [[ "$(< ${alsa_if_statusfile})" != "closed" ]]; then
+			## device is being used, get the locking pid
+			alsa_if_closed=1
+			res="$(get_locking_process "${alsa_if_chardev}")"
+			if [[ $? -ne 0 ]]; then
+			    ## can't determine
+			    [[ ! -z ${DEBUG} ]] && \
+				debug "${FUNCNAME}: get_locking_process returned error: \`${res}'"
+			    
+			    alsa_if_chardev="${alsa_if_chardev} (${MSG_ERROR_LOCKED_UNKNOWN}"
+			    alsa_if_formats+=("(${MSG_ERROR_DEVICE_LOCKED})")
+			else
+			    if [[ ! -z "${res}" ]]; then
+				alsa_if_chardev="${alsa_if_chardev} ${res}"
+			    fi
+			    ## can determine; get the formats the interface
+    			    ## natively handles or return the process id and
+    			    ## name blocking the interface
+			    alsa_if_formats+=("(${MSG_ERROR_DETERMINE_FORMATS})")
 			fi
-			## can determine; get the formats the interface
-    			## natively handles or return the process id and
-    			## name blocking the interface
-			alsa_if_formats+=("(${MSG_ERROR_DETERMINE_FORMATS})")
 		    fi
+		fi
+		## device is real and not being used
+		## check whether the monitor file exists; it always should
+		if [[ ! -f ${alsa_if_monitorfile} ]]; then
+		    msg="${alsa_if_monitorfile} ${MSG_ERROR_NOFILE} (${MSG_ERROR_UNEXPECTED})"
+		    alsa_if_monitorfile="${msg}"
+		    [[ ! -z ${DEBUG} ]] && \
+			debug "${MSG_ERROR_UNEXPECTED}: alsa_if_monitorfile \
+\`${alsa_if_monitorfile}' ${MSG_ERROR_NOFILE}"
+		fi
+		## check whether the streamfile exists; it only should
+		## exist in the case of a uac interface
+		if [[ ! -f "${alsa_if_streamfile}" ]]; then
+		    [[ ! -z ${DEBUG} ]] && \
+			debug "alsa_if_streamfile \`${alsa_if_streamfile}' \
+${MSG_ERROR_NOFILE}"
+		    ## no uac interface
+		    alsa_if_streamfile=""
 		else
-		    alsa_if_formats+=("$(return_alsa_formats "${alsa_if_hwaddress}")")
+		    [[ ! -z ${DEBUG} ]] && \
+			debug "using alsa_if_streamfile \`${alsa_if_streamfile}'."
+		    ## set interface to usb out
+		    alsa_if_type="uo"
+		    ## uac devices will use the stream file instead of
+		    ## hwparams file to monitor
+		    alsa_if_monitorfile="${alsa_if_streamfile}"
+		    ## get the type of uac endpoint
+		    alsa_if_uac_ep="$(return_alsa_uac_ep "${alsa_if_streamfile}")"
+		    if [[ $? -ne 0 ]]; then    
+			alsa_if_uacclass_nr="?"
+			alsa_if_uacclass_label="${MSG_PROP_NOTAVAILABLE}"
+		    else
+			[[ ! -z ${DEBUG} ]] && \
+			    debug "alsa_if_uac_ep set to \`${alsa_if_uac_ep}'."	    
+			## lookup the uac class in the array for this type of endpoint (EP)
+			## (for readability)
+			alsa_if_uacclass="${UO_EP_LABELS[${alsa_if_uac_ep}]}"
+			## the uac class number (0, 1, 2 or 3) according to ./sound/usb/card.h
+			alsa_if_uacclass_nr="${alsa_if_uacclass% - *}"
+			classnr_regexp='^[0-3]+$'
+			if [[ ! ${alsa_if_uacclass_nr} =~ ${classnr_regexp} ]]; then
+			    [[ ! -z ${DEBUG} ]] && \
+				debug "invalid uac class number \`${alsa_if_uacclass_nr}'. \
+${MSG_ERROR_UNEXPECTED}"
+			    alsa_if_uacclass_nr="?"
+			fi
+			## the uac label (ie everything after `x: ')
+			alsa_if_uacclass_label="${alsa_if_uacclass:4}"
+		    fi
+	    
 		fi
 	    fi
+	fi 
 
-	    ## check if the hwparams file exists
-	    if [[ ! -f "${alsa_if_hwparamsfile}" ]]; then
-		alsa_if_hwparamsfile="${alsa_if_hwparamsfile} (error: not accessible)"
-	    fi
-
-	    ## before determining whether this is a usb device, assume
-	    ## the monitor file is the hwparams file
-	    alsa_if_monitorfile="${alsa_if_hwparamsfile}"
-
-	    ## check if the interface name matches one of the strings
-	    ## in the digital filter array
+	## for non-uac interfaces: check whether it is some other digital interface
+	if [[ ! "${alsa_if_type}" = "uo" ]]; then 
 	    for filter in "${DO_INTERFACE_FILTER[@]}"; do
 		## `,,' downcases the string, while `*var*' does a wildcard match
 		if [[ "${alsa_if_name,,}" == *"${filter}"* ]]; then
@@ -440,55 +502,11 @@ function fetch_alsa_outputinterfaces() {
 		    break
 		fi
 	    done
-
-	    ## try to get the stream file for the interface (ie
-	    ## `/proc/asound/cardX/streamY'); such determines whether
-	    ## its a uac device, and if so, which class it is
-	    alsa_streamfile="/proc/asound/card${alsa_dev_nr}/stream${alsa_if_nr}"
-	    msg_alsa_streamfile="alsa_streamfile \`${alsa_streamfile}'"
-	    if [[ ! -f "${alsa_streamfile}" ]] ;then
-		[[ ! -z ${DEBUG} ]] && \
-		    debug "${msg_alsa_streamfile} ${MSG_ERROR_NOFILE}"
-		## no uac interface
-		alsa_if_uacclass="${MSG_PROP_NOTAVAILABLE}"
-	    else
-		[[ ! -z ${DEBUG} ]] && \
-		    debug "${msg_alsa_streamfile} is an accessible file."
-		## set interface to usb out
-		alsa_if_type="uo"
-		## uac devices will use the stream file instead of
-		## hwparams file to monitor
-		alsa_if_monitorfile="${alsa_streamfile}"
-		## get the type of uac endpoint
-		alsa_if_uac_ep="$(return_alsa_uac_ep "${alsa_streamfile}")"
-		if [[ $? -ne 0 ]]; then    
-		    alsa_if_uacclass="${MSG_PROP_NOTAVAILABLE}"
-		    alsa_if_uacclass_nr="?"
-		    alsa_if_uacclass_label="${MSG_PROP_NOTAVAILABLE}"
-		else
-		    [[ ! -z ${DEBUG} ]] && \
-			debug "alsa_if_uac_ep set to \`${alsa_if_uac_ep}'."		    
-		    ## lookup the uac class in the array for this type of endpoint (EP)
-		    ## (for readability)
-		    alsa_if_uacclass="${UO_EP_LABELS[${alsa_if_uac_ep}]}"
-		    ## the uac class number (0, 1, 2 or 3) according to ./sound/usb/card.h
-		    alsa_if_uacclass_nr="${alsa_if_uacclass% - *}"
-		    classnr_regexp='^[0-3]+$'
-		    if [[ ! ${alsa_if_uacclass_nr} =~ ${classnr_regexp} ]]; then
-			[[ ! -z ${DEBUG} ]] && \
-			    debug "invalid uac class number \`${alsa_if_uacclass_nr}'. \
-${MSG_ERROR_UNEXPECTED}"
-			alsa_if_uacclass_nr="?"
-		    fi
-		    ## the uac label (ie everything after `x: ')
-		    alsa_if_uacclass_label="${alsa_if_uacclass:4}"
-		fi
-	    fi
 	fi
-
-	## for each type of interface, store a `hardware address' and
-	## `monitoring file' pair in the proper array and construct
-	## the display title
+	## see if the interface type matches the user specified
+	## filters and if so construct titles and store a pair of
+	## hardware address and monitoring file in the proper array
+	match=
 	case "${alsa_if_type}" in
 	    "ao")
 		## only if neither `OPT_LIMIT_DO' and `OPT_LIMIT_UO' are set
@@ -505,9 +523,16 @@ ${MSG_ERROR_UNEXPECTED}"
 		[[ ! -z ${OPT_LIMIT_AO} ]] && \
 		    continue || match="true"
 	esac
+	if [[ ! -z ${match} ]]; then
+	    ## put each encoding format and possibily the sample rates
+	    ## in an array
+	    alsa_if_formats+=("$(return_alsa_formats \
+"${alsa_if_hwaddress}" \
+"${alsa_if_type}" \
+"${alsa_if_streamfile}")")
 
-	if [[ ! -z "${match}" ]]; then
 	    alsa_if_title_label="${ALSA_IF_LABELS[${alsa_if_type}]}"
+	    ## reconstruct the label if it contained square brackets
 	    if [[ "${alsa_dev_label}" =~ .*${seperator_start}.* ]]; then
 		alsa_dev_label="${alsa_dev_label//\*##/\[}"
 		alsa_dev_label="${alsa_dev_label//##\*/\]}"
@@ -529,6 +554,7 @@ ${MSG_ERROR_UNEXPECTED}"
 	fi
 
 	if [[ -z "${OPT_QUIET}" ]]; then
+	    ## print the list to std_err
 	    printf "%s\n" "${alsa_if_display_title}" 1>&2;
 	    printf " - %-17s = %-60s\n" \
 		   "${MSG_ALSA_DEVNAME}" "${alsa_dev_label}" 1>&2;
@@ -560,12 +586,10 @@ ${MSG_ERROR_UNEXPECTED}"
 		       "${MSG_ALSA_ENCODINGFORMATS}" \
 		       "${formats}" 1>&2;		
 	    fi
-	    
 	    printf " - %-17s = %-60s\n" \
 		   "${MSG_ALSA_MONITORFILE}" "${alsa_if_monitorfile}" 1>&2;
 	    printf "\n"
 	fi
-
     done
 }
 
@@ -576,7 +600,6 @@ function get_locking_process() {
     [[ ! -z ${DEBUG} ]] && \
 	debug_function_ac "${FUNCNAME}" "$*"
 
-
     chardev_path="$1"
     ## try fuser which returns the pid in std_out.
     res="$(${CMD_FUSER} -v ${chardev_path} 2>&1)"
@@ -672,52 +695,98 @@ LANG=C ${CMD_APLAY} "${aplay_opts_pre[@]}" "${aplay_opts_post[@]}" 2>&1 >/dev/nu
 }
 
 function return_alsa_formats() {
-    ## fetch and return a comma separated string of playback
-    ## formats by feeding aplay dummy input (--format=MPEG) while
-    ## making sure the test is silent by redirecting output to
-    ## /dev/null.
-    ## 
-    ## needs address of alsa output device in `hw:x,y' format 
-    ## as single argument ($1)
+    ## fetch and return a comma separated string of playback formats
+    ## for the interface specified in $1, of type $2. For non-uac
+    ## interfaces: feed dummy input to aplay (--format=MPEG). For uac
+    ## types: filter it directly from its stream file $3.
     [[ ! -z ${DEBUG} ]] && \
 	debug_function_ac "${FUNCNAME}" "$*"
 
     alsa_hw_device="$1"
+    alsa_if_type="$2"
+    alsa_if_streamfile="$3"
     aplay_opts=(-D ${alsa_hw_device})
     aplay_opts+=(-f MPEG)
     format=
     rawformat=
     declare -a formats
 
-    ## throw psuedo random but non-audio data to aplay while capturing
-    ## error lines starting with `- ' to determine formats
-    aplay_out="$(echo ${PSEUDO_RANDOM_NOISE} | \
+    if [[ "${alsa_if_type}" = "uo" ]]; then
+	## uac type
+	interface_re="^[[:space:]]*Interface[[:space:]]([0-9])"
+	format_re="^[[:space:]]*Format:[[:space:]](.*)"
+	rates_re="^[[:space:]]*Rates:[[:space:]](.*)"
+	inside_interface=
+	format_found=
+	while read -r line; do
+	    if [[ "${line}" =~ ${interface_re} ]]; then
+		## new interface found
+		[[ ! -z ${DEBUG} ]] && \
+		    debug "interface found: ${BASH_REMATCH[1]}"
+		inside_interface=true
+		continue
+	    fi
+	    if [[ ! -z ${inside_interface} ]]; then
+		if [[ -z "${format_found}" ]]; then
+		    if [[ "${line}" =~ ${format_re} ]]; then
+			## format for interface found
+			format_found="${BASH_REMATCH[1]}"
+			[[ ! -z ${DEBUG} ]] && \
+			    debug "format found: \`${format_found}'"
+			continue
+		    fi
+		else
+		    if [[ "${line}" =~ ${rates_re} ]]; then
+			## sample rates for interface/format found
+			inside_interface=
+ 			if [[ -z ${OPT_SAMPLERATES} ]]; then
+			    formats+=("${format_found}")
+			    format_found=
+			else
+			    samplerates="${BASH_REMATCH[1]//,/Hz}Hz"
+			    [[ ! -z ${DEBUG} ]] && \
+				debug "sample rates found: \`${samplerates}'"
+			    format="$(printf "%-18s" "${format_found}"): ${samplerates}"
+			    formats+=("${format}")
+			fi
+			continue
+		    fi
+		fi
+	    fi
+	done<"${alsa_if_streamfile}" 
+
+    else 
+	## non-uac type: throw psuedo random but non-audio data to
+	## aplay while capturing error lines starting with `- ' to
+	## determine formats
+	aplay_out="$(echo ${PSEUDO_RANDOM_NOISE} | \
 LANG=C ${CMD_APLAY} ${aplay_opts[@]} 2>&1 >/dev/null | grep '^- ')"
-    while read -r line; do 
-	rawformat="${line/- /}"
-	if [[ -z ${OPT_SAMPLERATES} ]]; then
-	    formats+=(${rawformat})
-	else 
-	    declare -a sorted_rates
-	    declare -a rates_supported
-	    [[ ! -z ${DEBUG} ]] && \
-		debug "#### try to get samplerates for format \`${rawformat}'"
-	    rates_supported+=("$(return_alsa_samplerates \
+	while read -r line; do 
+	    rawformat="${line/- /}"
+	    if [[ -z ${OPT_SAMPLERATES} ]]; then
+		formats+=(${rawformat})
+	    else 
+		declare -a sorted_rates
+		declare -a rates_supported
+		[[ ! -z ${DEBUG} ]] && \
+		    debug "#### try to get samplerates for format \`${rawformat}'"
+		rates_supported+=("$(return_alsa_samplerates \
 "${alsa_if_hwaddress}" "${rawformat}")")
-	    
-	    IFS=$'\n' sorted_rates=($(sort -u -n <<<"${rates_supported[*]}"))
-	    [[ ! -z ${DEBUG} ]] && \
-		debug "#### sorted_rates returned: $(printf "%s " "${sorted_rates[@]}")"
-	    rates="$(printf "%s " "${sorted_rates[@]}")"
-	    format="$(printf "%-18s" "${rawformat}"): ${rates}"
-	    formats+=(${format})
-	fi
-    done <<< "${aplay_out}"
-    #formats+=("${format#\n}")
-
+		
+		IFS=$'\n' sorted_rates=($(sort -u -n <<<"${rates_supported[*]}"))
+		[[ ! -z ${DEBUG} ]] && \
+		    debug "#### sorted_rates returned: $(printf "%s " "${sorted_rates[@]}")"
+		rates="$(printf "%s " "${sorted_rates[@]}")"
+		format="$(printf "%-18s" "${rawformat}"): ${rates}"
+		formats+=(${format})
+	    fi
+	done <<< "${aplay_out}"
+	#formats+=("${format#\n}")
+	
+    fi
     [[ ${#formats[@]} -gt 0 ]] && \
 	printf "%s\n" "${formats[@]}" || printf "${MSG_DEVICE_BUSY}"
-
+    
 }
 
 
@@ -734,7 +803,7 @@ function return_alsa_uac_ep() {
     ##   2: USB_DIR_IN: "IN|OUT",
     ##   3: USB_ENDPOINT_SYNCTYPE: "NONE|ASYNC|ADAPTIVE|SYNC"
   
-    alsa_streamfile_path="$1"
+    alsa_if_streamfile_path="$1"
     ep_mode=""
     ep_label_filter="Endpoint:"
     ep_label_regexp="^[[:space:]]*${ep_label_filter}"
@@ -756,7 +825,7 @@ function return_alsa_uac_ep() {
 		debug "matching endpoint found in line \`${line}': \`${ep_mode}'."
 	    break
 	fi
-    done<"${alsa_streamfile_path}"
+    done<"${alsa_if_streamfile_path}"
 
     if [[ -z "${ep_mode}" ]]; then
 	[[ ! -z ${DEBUG} ]] && \
@@ -1084,7 +1153,7 @@ MSG_ERROR_DEVICE_LOCKED="can't determine because device is locked"
 MSG_ERROR_DEVICE_BUSY="error: can't determine because device is in use"
 MSG_ERROR_DETERMINE_FORMATS="error: can't determine"
 MSG_ERROR_CHARDEV_NOFORMATS="can't determine: character device error"
-MSG_ERROR_CHARDEV_NOT_ACCESSIBLE="error: not accessible"
+MSG_ERROR_NOT_CHARDEV="error: is not a character device or not accessible"
 ## construct a list with the properties of the current
 ## interface if `OPT_QUIET' is not set
 MSG_ALSA_DEVNAME="device name"