A SET amp needs to be matched to loudspeakers since most SETs are low power even the largest are only 40 watts or so sure a few very costly exceptions. SETS have trouble with low ohm loads and if loudspeaker impedance is too low reduced bass and treble is usually the result. If SETs output power is not enough you will be clipping the amp most of the time. SET clipping isn't a square wave like SS amps so not damaging to loudspeakers like clipped ss amplifier. But you will have greater distortion again 2nd order not as bad sounding as distortions in SS amp designs. This is as simple as I can explain it. For loudspeakers consider Audiokeneses, KCS, Carter, Love craft, Omega. I own KCS just so you know;) The old bias to ones product. KCS can build custom if you like. We do have a SEAs exotic monitor that I actually use on my Mastersound 300b. And match's SET near as perfect as you can get in this hobie. KCS designs loudspeakers optimized for SET and using SETs in design and voicing stage We also design for all other amplifier types. Since amp loudspeakers should be carefully matched most manufacturers just design loudspeakers to be used with many types of amplifier thus not optimized for any. With SET many disappointed owners who where doomed from the start do to improper matched system. If you go hi-eff loudspeakers dont cheap out or even consider anything less than a 6in driver. Lots of hi-eff designs sporting cheap 4in drivers with special coating avoid these at all costs or you to will be doomed and back on forum. No 4in drivers is even close to fullrange. And talk about no frequency extremes or dynamic range. These weak little 4in drivers tend to chase away many from fully exploring SET hi-eff. Many - posts about hi-eff fullrange or SET can be traced to improper system match's or over expectations like expecting a wee 4in cone driven by 8 watts or less to move the earth ;) Same with horns many start cheap or use vintage and say colored sound and they are right,but Front horns can be near the best sound with SET you can get but are very large costly and not all are designed for SET use. Hard to get the best sound with SET unless crossovers simple and drivers are over built and mags very powerful this is not cheap to pull off. So to sum look for powerful mags ohm loads not below 4ohms. And with a 300b at least 90db 1 watt 8ohms.
