Klipschorns, 1210 … audio research classic 150s, a pair. Before that some other vintage valve amp
Can’t find the exact ome, but this is one of the big corner horns?
But Klipsch speakers almost invariably have a wild impedance curve, as can be seen from the samples shown here
https://community.klipsch.com/index.php?/topic/162238-klipsch-speaker-impedance-curves/
A valve amplifer (like a SS one) can be either push-pull (PP — like your Audio Research) or single ended. SE tuned amplifiers typically have high output impedance (R
ou) and in such cases the end output from the loudspeaker will have the impedance curve imposed on top of the FR curve.
PP tube amplifiers tend to have lower R
out, but not always. Here is the Ref 150 which i likely somewhat representative
output impedance varied according to the transformer tap selected. The 16 ohm tap measured 1.4 ohms at low and middle frequencies, rising to 1.9 ohms at the top of the audioband. The figures for the 8 ohm tap were 1 and 1.4 ohms; for the 4 ohm tap, they were 0.55 and 0.87 ohm. All three taps offer quite a low source impedance for a transformer-coupled design
So for best perfomance wiyth your loudspeakers an amplifier with lower R
out is likely best. SS amplifiers typically have even lower R
out.
You need very little power. 1 or 2 watts is likely more than sufficient for domestic levels.
I have both the little Class D (in my breifcase hifi) but the ACA minis i have are better (IMO). They can both be had cheap.
ACA mini is one of Nelson Pass’ many contributions to our community, one of the very best commercial impelementaions of the Class D chip is another member
@xrk971.
If you want to try SE the ACA is another very good amplifier and probably represents the best selling Pass amplifier so far (and all built by diyers)
dave