With 060 you will have no problems,
I use Songplayer with Paula 14bit, full quality, full bitrate
on a a1200 fitted in my car.
Can be controled with arexx with minor scripting.
I tested the performance of this system after reading your post,
and found I could run Songplayer twice at full quality,
one with paula sound and one with soundcard(AHI) at full bitrate
The system is A1200 68060/50 32Mb
I also tried this on my A4000 68060/50+PPC
and found I could run Songplayer three times at full quality
with no problems at all and the system was still responsive..