Bi-amping speakers

I’m contemplating using the 4 mono tube amps I have to bi-amp my speakers. They are different makes, how can I know if they are compatible for this. The equipment is:

2 McIntosh mc75 mono amps, vintage
2 Quicksilver silver 88 mono amps
1 PrimaLuna EVO 100 Tube Preamplifier.

Please give me as much information that can help me determine if it’s worth doing.


Input sensitivity relative to each other. May find the info online or in the manuals but may have to contact manufacturers.

2 McIntosh mc75 mono amps, vintage input impedance is 250k
2 Quicksilver silver 88 mono amps input impedance is 100k
1 PrimaLuna EVO 100 Tube Preamplifier output impedance is 2800 k.


Not the input impedance the input sensitivity. This is from the MC75’s manual

Input Sensitivity (for rated output)
1.7 Volt or 0.85 Volt Unbalanced
3.4 Volt or 1.7 Volt Balanced

The Quicksilver amp you own is not listed on Mike’s website so unless you have the manual you will have to call him though his amps are usually between 1 to 1.5 volts.

The manual states input sensitivity at 1 volt.

By the way thanks for the help.


O.K. then using the twin SE outputs from the Prima Luna you would be at 1 volt input sensitivity on the Quickie’s and .85 volts on each of the Mac’s so not perfect but close. Whichever section you put the Mac’s on is going to be slightly louder in theory though you may not perceive it so just try them both ways and pick the one that sounds the best on the top or the bottom. If you are using subs I might start with Quickie’s on the bottom where the volume would be slightly lower.

Glad to help

1 Like

The McIntosh have a gain dial, so maybe I can make adjustments.


Get TypeApp for Android

That should certainly help.