Pass Aleph P Feeding two amplifiers?

To be absolutely sure, you should contact the manufacturer.

I had a similar question when I wanted to do the exact same thing with a BAT VK3i so I contacted Viktor Khomenko. He confirmed that I could, but in that configuration the preamp would see the sum of the two amp's input impedances.

I don't know if this would be the same in your case, so check with Pass Labs.

Good luck!

The sum of impedances? That would mean they were connected in series.
Wouldn't it be the 1/(1/ImpA+1/ImpB).

If it is the sum, then the final impedance rises and that should be no problem. However, if they are connected in paralel, then the final impedance will be lower than the impedance of each amplifier.

I've asked Pass, but got no answer.

Sony,

I'm no tech, so I can't give you a thorough explanation.

But from my understanding of what's at work here, I'd assume you're right that if say one amp had an input impedance of 27Kohms and the second were 47Kohms the resulting 74Kohm seen by the preamp would work out well in most situations. Especially considering that some solid state amps have input impedances of 100Kohms. At least this is the case with the BAT VK3is that have both RCA and XLR outputs.

Hopefully, Pass Labs will get back to you soon.

I would think there should be no problem.

I used an Aleph P to drive a pair of Bryston 7B STs via the balanced outputs while connecting the single ended outputs to an equalizer which was fed into the single ended inputs on the Brystons. (This let me switch the equalizer in and out using the source switches on the back of the monoblocks.) Accordingly, the Aleph P output saw the combined impedance of the inputs of the power amps and the equalizer. To me, there was no difference in sound between this set up versus having only the balanced connection.

While I agree with the formula for impedance that you posted, I would point out that the balanced connection will produce a slightly louder volume (by about 6 db?), since a balanced connection is inherently louder than single ended. This is worth noting if you are thinking about running four amp/speaker combinations simultaneously off the Aleph P. Of course, the definitive answer will come from Pass. Good luck.

I use the balanced to run a pair of Aleph 2 monos, but interestingly use the RCAs to directly run my Senn HD600 quite successfully. Ern

Thank to all for the answers.

Subaruguru, are you driving two pairs of loudepeakers or bi-amp?

I use the balanced set to drive a Krell FPB 200, and a single RCA to drive my subwoofer amp. The active devices in the Pass Aleph P are power mosfets. Check the specks...I think it will act as a 20 ma max +- current source into a dead short.

No. Just the Aleph 2s and the 'phones. Ern