Bass leaves after amp warms up?

I petitioned my dealer to lend me a dedicated 250 w amp from Musical Fidelity. Do you feel this will resolve the problem?

Could be, but I'm by no means certain. I would expect it to be more capable of handling low impedances than the integrated amps you've used, but once again it unfortunately does not appear to have a 4 ohm power rating.

I use Marantz Professional cd recorder CDR400 w/built in mic.

Couldn't find any info on a Marantz CDR400, but I did find this on the CDR420. If it is the same as or similar to that model, it does provide both AGC (referred to in the writeup as ALC) and peak limiting. To obtain recordings that are as meaningful as possible for present purposes, both of those functions should be switched off, and the recording level set such that the maximum level that is reached during the track at any time (whether or not the problem is present) is several db (perhaps 6 db or so) below the 0 db reference point. All settings should then be left exactly the same for both recordings.

Regards,
-- Al

I admire all you kind people you have tried to help a brother out. Also, who doesn't love a good mystery.

Fishing, it would be great to test your system with the MF
M6PRX Power Amplifier. Once again, they give no power rating into 4 ohms; but state 260 wpc/8 ohms and claim it provides high current (around 140 amps), with a peak voltage output of 130 volts. This will drive those PSBs.

I keep thinking about the impedance curve of these speakers, and I think this has played a major factor in your problem. (or inconsistent line voltage).

Also, some advice...you should leave a SS amp powered-up 24/7. Those who don't always let the amp warm up one hour before any critical listening.

Good Luck.

My apology
Marantz CD Professional CD Recorder CD300

I absolutely leave the amp powered up much as possible including overnight..

My comments about the CDR420 also apply to the CD300. Looks like it has a front panel switch that selects between ALC, Manual, and Limiter. It should be set to manual, and the recording level set such that its volume meter never gets near the 0 db full scale reference point during any of the recordings. On the other hand, if you set the recording level too low, then noise levels will increase, relative to signal levels, which is why I suggested allowing a margin of perhaps 6 db or so, relative to the 0 db reference point.

Regards,
-- Al