Which preamp to go with pass labs x150.8

I owned an Audio Research Reference 5SE for nearly ten years… marvelous preamp.  If I had not upgraded the rest of my system and in the process my ARC to REF6se, I would still be very happy with it. For much of that time I had a Pass x350. A very happy combination.

@panerai557 Your amplifier has balanced inputs. If you want to get the most out of them, the preamp should support AES48 which is the balanced line standard. To the best of my knowledge, ARC has never made such a preamp despite being balanced.

An important tenent of AES48 is that the ground (shield) isn't part of the audio circuit connecting the preamp to the amp. Its only a shield. The actual audio signal is a twisted pair that's inside. This helps give you a lot of cable immunity as well as ground loop immunity.

There are tube preamps that support AES48 FWIW. I would widen your search.

I love the refinement and spaciousness of the sound of a good tube preamp.  My Cary Audio SLP 05 in front of the Pass XA25 sounds incredible.   It should also work well with the X150.8.  

I wouldn’t worry about the age of the unit and get either the Ref5 or Ref5SE if you want to try an ARC  preamp. 

no doubt pairing tube pre with ss power amp has been a well known much practiced recipe for audio happiness for ages

c-j and arc are tubed pre stalwarts, impeccable sound and quality, forever units from forever companies standing behind them

once again, it depends on what one is desiring the linestage to do sonically... even if one wants tubey goodness in the chain, is the linestage where it is introduced? there are wonderful tubed phono stages and dacs... you get the drift...