Originally Posted by kaigoss69
Hmmm, interesting. I've got the OEM sides/rears in parallel (1 ohm) running off one channel pair on the HD900/5. The fronts (4 ohm) are driven by the HD600/4. With gains set to minimum on "low" (2V) the rears are a few dB louder than the front doors. Theoretically, the max output of the HD900/5 at 1 ohm is 75W and that of the HD600/4 at 4 ohm 150W, so the fronts should be a lot louder, but they are not. I'm not worried about it though since I can raise the gains on the front channels to compensate.
The "low/High" input switch discussion though has got me thinking. I've had a problem with noise on the HD900/5 amp. When I switch from low to high, the noise goes away but of course the output level gets reduced and of I raise the gain to compensate, the noise comes right back. I was thinking, since the MS-8's speaker level outputs are of very good quality, what if I used those instead of the low level RCAs? Any potential downsides to doing that? This may be a good solution since it would kill 2 birds with one stone - getting rid of the engine noise AND utilizing the reportedly superior input option on the HD amps.
I do not see a problem with that as the speaker outputs of the MS-8 are about 60W at 2ohms already. And because the rear speakers are there just for surround effects (Logic7 processing on) and high passed then there's no real need of higher power going there.
-2012 E92 M3 Jerez Black/Rust Brown, M-DCT: September ED
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