All, I saw this post on audiogon and I thought it will be a very interesting comparison. But I will not have time to try it myself because I'm too busy moving. I wonder if anyone has done the comparison?

I copy and paste the entire post here:

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Let's say we have two identical units of MC275 (unit A and unit B). And the speakers are designed for bi-amping.

There are two different ways of running them in mono:

(1) Assuming your preamp has two identical sets of left/right outputs (i.e. L1/R1 and L2/R2). First, connect L1 to the left input of unit A; secondly, connect L2 to the right input of unit A; next, connect the left output (+ and -) of unit A to the high-pass binding posts of the left speaker; and finally, connect the right output (+ and -) of unit A to the low-pass binding posts of the left speaker. For two speakers, this configuration requires 2 pairs of interconnects and 2 pairs of single speaker wires (no jumpers required).

(2) This is the 'conventional' way of running mono. First, connect L1 to the left input of unit A; then use jumper cables to link the left and right outputs of unit A; then connect speaker cables from either the left or right output of unit A to the speakers.

Have anyone tested both configuration? And if so, please share your experience.

This question was asked in a different way before but can't find the post - effectively you are passively bi-amping in the first scenario - Ron C (I think) strongly advised against this as the tubes are not properly loaded across the full frequency range and don't like to be driven in that way.

Another disadvantage with the first scenario is that each driver only has 75 watts to play with - if you run the 275 as a mono unit then there is twice that power available at any frequency.

I use mine for center channel in Mono.