Amp for Swans M1S


I am looking for an amp that will power my Hi-Vi Research Swan M1S Speakers.
The specs are as follows:
Power: 10-60W
Sensitivity: 86dB/1m/2.83v
Impedance: 8ohms
Frequency 48Hz-20kHz

I am hoping to buy used and keep it under $300 preferably. Vintage or newer is fine, tube or solid state is also fine.

I would really like something that delivers a fast slew rate/speed to get that nice articulation of attack and decay on notes, as well as good, tight power and punch, particularly in the mid range. I am really trying to avoid the thin/dry and boring sound - I want something musical, baby! Think body or fullness!

Thanks in advance! Any opinions or suggestions are greatly appreciated.

p.s. I mostly listen to classical music, and singer-songwriters like Norah Jones. Occasionally electronica/trip-hop and punk rock (clash, BR, etc.) - but who cares how that sounds as long as it is loud and obnoxious :)

Thanks again.