Pass amp paired with audio research pre?

Thank you for your note! Hypothetical. Trying to think about where I should go with future purchases. I live in the sticks. Not much opportunity to listen to other components. I try to read and ask questions.

Been thinking about audio research reference 5SE, Audio research reference phono 3, pass labs 250.8.

I have a VPI classic 4 with a transfiguration Proteus cartridge…

@fanotunes
If you are thinking about solid state Pass Labs is a very good choice, but since you already have the RM200, I see no point in changing out the amp- the RM200 is pretty neutral so I would not think for a moment that is is responsible for the excessive laid back quality.

Before changing anything out, I’d consider replacing the tubes in the line stage and possibly the input tubes of the amp. Its common if those tubes get weak for the preamp or amp to get a bit ’sleepy’- which might be easily described as ’too laid back’. You may find no need to do anything else once that is done!


After making sure those tubes are not an issue, I would then investigate the phono cartridge loading. The loading is there for the preamp, not the cartridge- its meant to prevent ultrasonic or RF resonance inherent in all pickups from messing with the preamp. The correct loading (if the preamp is sensitive to RFI; ours are not so no need for the loading with LOMC cartridges;) is the **highest** value that prevents the resonant circuit caused by the cartridge inductance and the tone arm cable capacitance from going into excitation. Since each cable is different (and thus the capacitance is not predictable), cartridge manufacturers make worst case recommendations; this can result in a duller presentation, since the loading resistor means the cartridge has to do more work. This in turn results in a stiffer cantilever that is less able to trace high frequencies. That is why its advantageous to work with a preamp that does not have the RFI sensitivity in the first place- and then no need for a loading resistor.

I think it will work great, just make sure the "output impedance" of the AR preamp is at least 10 x lower than the "input impedance" of the Pass amp.

The thing to look at is the output impedance at 20Hz, which is often considerably higher than it might be at 1KHz.

@fanotunes
Any particular reason the preamp has to be ARC?


ARC does not recommend driving an amp with less than a 30K input impedance. Pass Lab X series amps are lower than that (22,000 ohms according to their owner's manual), so bass will suffer and distortion will be higher.

If I were you I would look elsewhere. There are balanced tube preamps out there that have no problem driving Pass Labs amps at all and as a result IMO sound better as well.


There is a standard for balanced line operation (a.k.a. 'AES48'). The standard is there to insure that balanced sources will work with balanced inputs on things like power amps. Most high end audio preamps don't support the standard; not sure if they don't know it exists or simply chose not to. But in a case like this it makes a difference- if ARC supported the standard then you could just plug and play. There are tube preamps that support the standard.


Another aspect of the balanced standard is that it is effective at eliminating interconnect cable artifacts. If you've ever heard two cables sound different, or heard of that phenomena, you know what I'm talking about. This means you don't have to spend a lot of money on the cable and you can run it much longer distances, although you get the benefit of balanced operation even if the cable is only 6 inches.


In case you think I'm slamming ARC I'm not; you were asking about whether it would work. They are not alone in not supporting the standard. I can't think of a good reason why not (sound quality isn't one of them) unless it was just too hard to do, something like that.