Rogue Audio Atlas Magnum III Power Amplifier

The Rogue amps perform really well from their 4 ohm taps into 8 ohm nominal speakers, so a 3 ohm dip shouldn’t be any problem when running from those taps. But the Stereo 100 should perform better overall, if you can go there.

100 Watts, even sacrificing a little of that for running 4 ohm taps into 8 ohms (this mismatch will generally sacrifice some power in exchange for lower distortion and better bass), should be enough for you 93dB speakers.

I like the A21 (owned one in the past) but I think the Rogue amps will be more enjoyable. They also bring a lot of flexibility for tube rolling, etc.

I had an original Atlas and compared it to a Stereo 90 in my system, long ago. Yeah, the ST90 was definitely better (I later upgraded to Apollos). So I agree with @avanti1960 - you should probably just stretch to the Stereo 100. 

@couger4u 

I've tried the Apollos in triode, they still have plenty of power that way (150 Watts into my 96dB speakers) but the sonics just don't do it for me. I prefer ultralinear every time. The triode mode gains you like 1% worth of a sweeter midrange, at the expense of significant bass power, slam, and dynamics. IMO the Rogue amps sound like they're supposed to in ultralinear. If you want a super sweet lush tube amp, these aren't that.

And no, you definitely should NOT use KT150 in any Rogue amps. Even in amps that can use them (like my VACs) I think they will not sound good unless the amp was designed specifically for that tube. They sounded bad in my VACs.