For several years I used to compare 3 amps in my main system by using Tightening Banana Jacks.
A pair of jumpers from my speakers to a wall hook easy to reach each side without bending.
3 sets of color coded speaker wires with these

1. McIntosh SS MA2250 (tested accurate at 305 wpc)
2. Fisher 500 C Tube Receiver (30 wpc)
3. Fisher Mono Blocks 80AZ, 1958 (30 wpc)
Everyone chose the Tube Receiver over the SS, and the Tube Mono Blocks over the Tube Receiver.
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And the same music CD; LP; Reel to Reel (7-1/2 IPS pre-recorded)
Everyone chose LP over CD, and R2R over LP.
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I’m gonna sell the Fisher 500C Tube Receiver, and I just found this gizmo which will switch two amps and/or switch 2 pairs of speakers. $120. I ordered one, comes Monday. I don't need to compare, I just want to demo the Fisher in my system for a 'local pickup' buyer.
https://www.amazon.com/dp/B0CZRMSHJB

Might be crap, might be transparent, I’ll get some friends to listen with me.

