Which power amplifier match audio research ref 3

I have a great respect for this preamplifier. It introduced me to a new level of sonic pleasure.
I am combining the Ref 3 with a Pass Aleph 5 and am satisfied with the combo.
The Aleph 5 is a 60W solid-state, class A, single-ended amp. I prefer the sound of the Aleph 5 (or Aleph 3) over all the solid-state class AB and/or push-pull amplifiers I've heard. Midband purity is exceptional for a non-tube amplifier. I also own an Aleph 3 but it does not combine well with the Ref 3, maybe because I am using the Aleph 5's XLR connection which provides an higher gain (26dB over 20dB on the Aleph 3 that only has RCA inputs).

In the combo Ref 3/Aleph 5 there is some loss of bass control and definition, but just a little more than when pairing the Aleph 5 with solid-state pre-amplifiers (it's more an Aleph 5 limitation). On the other hand the Ref 3 provides much better soundstage, truly natural midband and correctness and realism of all instruments and voices. For instance, replacing the Ref 3 with an Aleph P, the sound loses all this magic and seems artificial.

Note that the Aleph 5 works particularly well with easy loads. This amp requires very carefully speaker matching. I would forget any hard loads. The speakers I am using in this setup have a sensitivity of 94dB and 6ohm nominal impedance. Source is Mark Levinson.

As commented here, probably there is no better match than the ARC VT100 mkIII or the Ref 110 (which I would like to try one day), especially on the low-end. However, these come along at a 5K price against 1.5K for the Aleph 5.
So, the Aleph 5 can be an interesting option if money is an object and speakers are easy to drive. An easy ticket for a magic midband.

I totally agree with Atmasphere's balanced/differential observations. That's how the Ref 3 shows its full potential.
However I am not so sure on the impedance-match limitation.
The Aleph 5 input is only 25Kohm balanced differential, quite bellow the 100Kohm suggested mark. It's a great match with my easy speakers. Magic midrange and great dynamics.
Additionaly, if you check Stereopile's measurements of the Ref 3, it is inferred the distortion is very low on loads above 10Kohm.
As stated before, the most common mismatch is power-amp/speakers.

A dealer is announcing a new Ref 75 power amp (only balanced inputs as usual in the Ref series). Although quite expensive, this may also be a great match.