3 amplifiers inputs connected in parallel (1 Viewer)

[John H]

I am putting together a dedicated headphone system. It will have 1 SS and 2 tube headphone amplifiers.

What load will these 3 amps connected in parallel present to my source player?

Imput Impedance

1. 55K
2. 100K
3. 100K

Final load 26K?

Will the load change if any combination of the 3 amps are not powered on? My player specifies a load of >10K.

Would a parallel configuration be acceptable or should I install a line switcher?

John

 

[Mark Tranchant]

Yes, 26Kohm - assuming the input impedance is constant with frequency on all three amplifiers.

The combined input impedance with amps powered off depends on the circuitry used. Simple op-amp input stages would not change significantly when powered off, and I wouldn't expect any circuitry to reduce its input impedance when off.

You should be OK, but watch out for grounding differences bewteen the amps. Properly-deisgned stuff should be OK, but cheap stuff may have significant "signal ground" voltage differences, which you'll be connecting together.