REVIEW: Pass Labs XS 150, XA160.8, XA160.5

[microstrip]

Yes it seems the new.8 and XS are all higher input Imp. Compared to the .5

Yes, Stereophile reported 17 kohm for the input impedance of the XA60.5, either balanced or unbalanced. The REF4 or REF10 would easily drive it, as it has several triodes in parallel in the output stage. But I am am not aware of the REF6 topology.

 

[bonzo75]

Yes, Stereophile reported 17 kohm for the input impedance of the XA60.5, either balanced or unbalanced. The REF4 or REF10 would easily drive it, as it has several triodes in parallel in the output stage. But I am am not aware of the REF6 topology.

It cannot drive 17k. The output impedance of AR swings to 3 - 4k at some frequencies. The input impedance for AR power amps is around 300k, which is fine. An AR pre on a 20k power amp will make it ound thin in the midbass

 

[bonzo75]

The VTL 7.5 is 25 - 150 ohms, the Ypsilon is 150, Nagra is low too.

 

[microstrip]

It cannot drive 17k. The output impedance of AR swings to 3 - 4k at some frequencies. The input impedance for AR power amps is around 300k, which is fine. An AR pre on a 20k power amp will make it sound thin in the midbass

AFAIK it is not as high as you are referring - the minimum is around 1300 ohm at 20 Hz compared to around 600 ohms at midband, giving a negligible attenuation of around 0.5 dB at this low frequency. I rember well that Jeff Dorgay of Toneaudio successfully tested the Burmester 911 mk3, that has a very low input impedance, with the REF5 SE.

Although I would prefer to use such tube preamplfiers with high impedance input amplifiers, in reality it seems that the real way to know is listening!

 

[bonzo75]

In reality, I don't like AR (after owning Ref 3 and Ref 110), did compares, and have also compared Ref 10 to koda, but I didn't want Rio bring my subjective preferences in.

 

[Argonaut]

In reality, I don't like AR (after owning Ref 3 and Ref 110), did compares, and have also compared Ref 10 to koda, but I didn't want Rio bring my subjective preferences in.

You just have!

 

[bonzo75]

You just have!

That was a reply to micro's "reality is in listening"

 

[alfa100]

I heard ARC Ref 5 with pass 100.5 once and it sounded overly warm and soupy. The Xa.8 and Xs have 200K input impedance the .5 only has 20K. Even though that is well withing the ARC guidelines i would Try before I buy!

This is from the Arc website to the Ref10 : If your solid state Amp fits that bill you can give it a go:

OUTPUT IMPEDANCE
600 ohms Balanced, 300 ohms SE main (2), 20K ohms minimum load and 2000pF maximum capacitance. Outputs (3): 2 main, 1 tape (XLR and RCA connectors).

ditto

i heard Audio Research ref 5 with Xa 100.8 and found it too syrupy. maybe the Ref 5 se is better .

 

[analog brother]

have heard xa30.8 with 5se.
fantastic combo.