notice default sink/source in "info" output.

$ pactl info
Server String: /run/user/5271/pulse/native
Library Protocol Version: 35
Server Protocol Version: 35
Is Local: yes
Client Index: 1785
Tile Size: 65472
Server Name: PulseAudio (on PipeWire 0.3.54)
Server Version: 15.0.0
Default Sample Specification: float32le 2ch 48000Hz
Default Channel Map: front-left,front-right
Default Sink: bluez_output.00_18_09_2F_E5_54.headset-head-unit
Default Source: bluez_input.00_18_09_2F_E5_54.headset-head-unit
Cookie: 93b0:726c
________________________________________________________________

device summary, last device known to the "list cards" command.

$ pactl list cards
Card #1413
	Name: bluez_card.00_18_09_2F_E5_54
	Driver: module-bluez5-device.c
	Owner Module: n/a
	Properties:
		api.bluez5.address = "00:18:09:2F:E5:54"
		api.bluez5.class = "0x240404"
		api.bluez5.connection = "disconnected"
		api.bluez5.device = ""
		api.bluez5.icon = "audio-headset"
		api.bluez5.path = "/org/bluez/hci0/dev_00_18_09_2F_E5_54"
		bluez5.auto-connect = "[ hfp_hf hsp_hs a2dp_sink ]"
		bluez5.profile = "off"
		device.alias = "MDR-ZX330BT"
		device.api = "bluez5"
		device.bus = "bluetooth"
		device.description = "MDR-ZX330BT"
		device.form_factor = "headset"
		device.icon_name = "audio-headset-bluetooth"
		device.name = "bluez_card.00_18_09_2F_E5_54"
		device.string = "00:18:09:2F:E5:54"
		media.class = "Audio/Device"
		factory.id = "14"
		client.id = "101"
		object.id = "59"
		object.serial = "1413"
	Profiles:
		off: Off (sinks: 0, sources: 0, priority: 0, available: yes)
		a2dp-sink: High Fidelity Playback (A2DP Sink) (sinks: 1, sources: 0, priority: 16, available: yes)
		headset-head-unit: Headset Head Unit (HSP/HFP) (sinks: 1, sources: 1, priority: 1, available: yes)
		a2dp-sink-sbc: High Fidelity Playback (A2DP Sink, codec SBC) (sinks: 1, sources: 0, priority: 18, available: yes)
		a2dp-sink-sbc_xq: High Fidelity Playback (A2DP Sink, codec SBC-XQ) (sinks: 1, sources: 0, priority: 17, available: yes)
		headset-head-unit-cvsd: Headset Head Unit (HSP/HFP, codec CVSD) (sinks: 1, sources: 1, priority: 2, available: yes)
	Active Profile: headset-head-unit-cvsd
	Ports:
		headset-input: Headset (type: Headset, priority: 0, latency offset: 0 usec, available)
			Properties:
				port.type = "headset"
			Part of profile(s): headset-head-unit, headset-head-unit-cvsd
		headset-output: Headset (type: Headset, priority: 0, latency offset: 0 usec, available)
			Properties:
				port.type = "headset"
			Part of profile(s): a2dp-sink, headset-head-unit, a2dp-sink-sbc, a2dp-sink-sbc_xq, headset-head-unit-cvsd
________________________________________________________________

counterexamples, using ITS OWN CHOICE OF NAMES JUST ABOVE:

$ pactl set-card-profile bluez_input.00_18_09_2F_E5_54 a2dp_sink
Failure: No such entity
$ pactl set-card-profile bluez_output.00_18_09_2F_E5_54 a2dp_sink
Failure: No such entity
$ pactl set-card-profile bluez_card.00_18_09_2F_E5_54 a2dp_sink
Failure: No such entity
$ pactl set-card-profile bluez_card.00_18_09_2F_E5_54.headset-head-unit a2dp_sink
Failure: No such entity

maybe the alias name will work.

$ pactl set-card-profile MDR-ZX330BT a2dp_sink
Failure: No such entity

why, no, of course not. how silly of me, to expect that an alias could be used as ... an alias.

how do i name this damn thing so that pactl won't piss all over it?!?