Guess we could share what speaker we use we our setups.
Of course, there is the cheap Mono Enclosed Speaker - 3W 4 Ohm. Nice and cheap for testing, but sound is really poor.
Personnally, I tried different bluetooth and usb speaker and finnally I use the same on all snips master/satellites and rhasspy test config. I have them plugged in respeaker 2 mic hat jack.
Once plug, it never goes to stand-bye, so you can always send TTS on it even after hours of inactivity.
If you go for a bluetooth/usb speaker, you must check that you can turn off auto-off / stand-bye feature. This feature is compulsory in Europe but not all have a way to disable it.
I also have my snips master set with equal ALSA plugin : https://github.com/KiboOst/SNIPS-Tips/tree/master/snips_equal
Didn’t tried it yet with rhasspy, as even picoTTS sound correct with the metallix.