Hi, thinking of trying S5's (8 ohm) on 4 ohm tap of Eico HF-81, is this a no no , what are the dangers or any advantages? Thanks
I don't think it will damage anything, but you may not get the full power out of the Eico that way. I think it depends on the voltage output capabilities of the amp. You will likely have a better (higher) damping factor, due to lower source impedance, but this will probably not make a sonic difference.
The frequency response may be affected (it might roll off the treble, or even accentuate the treble ...). I don't know enough about all this stuff. Actually, I guess if the damping factor is better, and the speaker's impedance varies a lot, it could 'smooth out' the frequency response (make it sound flatter across the spectrum).
If you don't usually crank the sound to max volume, it will likely be fine (no power limitations). Will it sound better? Don't know. Interesting experiment. Let us know!