So it's not as easy as preout 1 of the c22v to a 1502 for m/h and the preout 2 to whichever other amp for lows
Yes, and no.
Provided it is sanctioned by McIntosh, which might run afoul of people not willing to “stick their (collective) necks out” to approve it, this I have found to have its advantages and improve SQ in systems I had before I had line-level crossover options (DSP etc.). However the amplifiers I used for this were Solid State / direct-output and had no oscillations etc. from the frequency range of the music not having a significant load to draw it down and prevent this oscillation.
Modern McIntosh, perhaps all McIntosh since the ‘60s, in my experience has a robust enough design that this is not a problem. However my experience/opinion is NOT an endorsement as I have not owned any modern McIntosh tube gear (a choice), nor have I studied the design/schematic of any modern McIntosh tube gear. There are a few people on this forum who post regarding tube circuits who I feel are qualified to make this determination as they spend a lot of time in tube gear theory and design, I do not.
So what’s all the fuss? I’ll put in my words what this is about:
When your amplifier, as it is currently used full range into a full range speaker system puts out all of that music, it is divided into two (or sometimes more) loads, a high-pass filter allows the HF to go to the HF driver(s) and doesn’t pass the LF music to these drivers, essentially looking like an open circuit for the LF frequencies. There is a low-pass filter that passes the LF music from the amplifier to the LF driver(s), so there’s somewhere for all of that LF energy to go.
All of the energy potential from the amplifier has a “path to ground”, a way to be dissipated from an amplifier attached to a full-range speaker. The impedance match that
@62caddy mentioned above.
In a biamplified system this is not the case. In a “passive biamplified” arrangement, you are sending full-range music to each amplifier, and the portion of the music that is not driving the speaker, does not have a load and in theory, can create oscillation and other trouble in the amplifier’s output transformer.
In a simple transformer I can certainly see this to be true.
However, McIntosh’s bifilar winding and autoformer design is intended to prevent lots of bad stuff, on top of that there is a significant amount of NFB. Negative FeedBack is in simple terms the distortion in the output as compared to the audio input, inverted and fed back in to cancel the distortion. In theory, since this is wideband NFB, any oscillations or other bad stuff that are in the output of the transformer (and therefore are not part of the music) will be cancelled by this NFB scheme and therefore not a concern. In theory and according to me, based on knowledge of general McIntosh design principles, not specifically the MC1502.
Passive biamping is not preferred nor considered best practice, and McIntosh should be able to tell you if this amplifier can be used in this way. If you’re looking at buying from Audio Classics (a well-regarded McIntosh dealer here) they also should be able to give you an informed opinion on this.
Best of luck
Still, I’m not a tube fan, and since anything tubes can do, SS can do better (ex: The Bob Carver Challenge) so I’d still say skip the maintenance and go right to the MC352/MC452/MC402/MC462 and you will have enough to keep your speakers happy at all reasonable levels with excellent-accurate power, and even the lighting on these (except possibly the 402) is LED so maintenance is not necessary for the foreseeable future.
