Bass leaves after amp warms up?

In addition to the experiments that Ralph (Atmasphere) suggested, if readily practicable it may be worthwhile to try running the amp with its top cover removed, which would lower its internal temperatures.

You would suggest I get 8ohm speakers?

If you are happy with the sound of the speakers during the first hour, and if the conclusion is reached that either the speakers or the amplifier has to be changed, it would probably make the most sense to either change the amplifier, or to purchase a separate power amplifier and drive it from the M6i's pre-outs.

Regards,
-- Al

I go back to my original assertion. As Almarg says the results suggest that these amps could not hack it with these speakers (not a good match into a 4 ohm load). I would look at trying an amp with the PSB'a that doubles its power into 4 ohms. (high current)

Ooops. TO3 mosfets.

Can you suggest integrated amps that double it's power into 4 ohms
Not Bryston or Musical Fidelity..I'm not familar with other integrateds

Atmasphere
After enjoying the system sounding great for 2 hrs the bass dried up.
I waited 1 hr.tried again but no improvement.
Turned off amp for 1hr.returned & the presentation was still awful.
I also observed when I change source on the amp it seems to create a break in the circut & the bass leaves soon after.
I've sometime observed after turning a record around/changing channels on a cable box or changing imput buttons on the amp may upset the delicate balance.