the First Watt amps are pretty plentiful and all are low power SS designs
the 47 Labs GainCard (and the clones) are much less plentiful than in years past but another good option
Also the AudioSector amps (again hard to find used)
Some of my favorite vintage SS:
Rowland Model 1
Levinson 29
Krell KSA50s
Plinius SA50 mkIV
Also there is a AirTight (Acoustic Masterpiece) M-101 TUBE amp of 8W on AudiogoN now that IMHO is NOT a classically "tube sounding" amp (I own one but am not the seller of this one)
the 47 Labs GainCard (and the clones) are much less plentiful than in years past but another good option
Also the AudioSector amps (again hard to find used)
Some of my favorite vintage SS:
Rowland Model 1
Levinson 29
Krell KSA50s
Plinius SA50 mkIV
Also there is a AirTight (Acoustic Masterpiece) M-101 TUBE amp of 8W on AudiogoN now that IMHO is NOT a classically "tube sounding" amp (I own one but am not the seller of this one)