connecting mono amps to pre amp

You're welcome, 2channeladdicted.  Just be sure to keep in mind the following statement in the 2120's manual:

Should the MODE SWITCH be left in the STEREO position and the output transformers be strapped for a monophonic load, one channel will attempt to drive the other and cause circulating currents and overheating. Be certain that the MC 2120 is never operated in the stereo mode with the outputs connected for monophonic operations.

Regards,
-- Al
 

So it should be placed in the MONO mode that has MONO(L+R)  Correct??

The 2120's in MONO switch in back, and the MA 6100 on the front side that has the mode switch and have it switched to MONO (L+R)

The switch on the rear of the 2120 that selects between stereo and mono should be set to mono, as has been said.

The mode selector switch on the front panel of the 6100 should be set to stereo, assuming you are listening to a stereo recording. Setting it to mono would result in both speakers putting out the same sound, corresponding to the sum of the two channels of the recording. Assuming you are playing a stereo recording, what you want is for the left speaker to play the left channel of the recording and the right speaker to play the right channel of the recording. No damage would result, though, regardless of which of those positions the switch is set to, and regardless of whether a stereo or a mono recording is being played. The result would just be that the sound and the imaging would not be right, if you were to play a stereo recording in mono mode.

If you are playing a mono recording though, it would be preferable to set the mode selector switch on the front panel of the 6100 to mono, although it might not make much difference if you leave it in stereo.

Regards,
-- Al

Not to confuse you, but since you already own both amps, you may want to try a vertical biamp. (I'm assuming your speakers have 2 pairs of binding posts). For the most part, people feel that bridging a stereo amp degrades sound quality. How much will vary from system to system. A vertical biamp will allow you to use both amps unbridged and avoid any power differences that usually come up with horizontal biamping.

If you want more info, have a look at this.

http://vandersteen.com/audio-perfectionist-journal

Personally, I think APJ is the best reference on high end audio ever written. There's an incredable amount of useful information in it.