I've had a pair of 804's for about 8 months. I've used them with SimAudio P-3 and P-5 preamps, and for amplification I've used an older SimAudio 4070 as well as a used Sugden Au51p. Both amps worked quite well. The Sugden is a 10 year old design, with lots of class A bias and good current delivery. I have had very good results using it on the 804's - it sounds tomally richer and more dynamic than the 4070. In terms of new solid-state gear, I'd probably recommend the SimAudio P-3/W-3 combo as providing a very high level of transparency, warmth, and dynamics for the price.
However, the very best I've heard my 804's sound is with a tube integrated. But not just any tube integrated - the KR18 BSI from KR Audio. It uses the 300BXLS tubes and puts out about 20 wpc with excellent current drive. This amp drives the 804's to near perfection, with smoother highs, more dynamics, a richer midrange and much better bass than any SS combo I've tried. It makes them into very musical speakers indeed.
However, the very best I've heard my 804's sound is with a tube integrated. But not just any tube integrated - the KR18 BSI from KR Audio. It uses the 300BXLS tubes and puts out about 20 wpc with excellent current drive. This amp drives the 804's to near perfection, with smoother highs, more dynamics, a richer midrange and much better bass than any SS combo I've tried. It makes them into very musical speakers indeed.