Mc 240 vs. Prima Luna

I've heard the nasty downside of bridging, with solid-state amps which I loved in stereo mode (Phison A2.120 SE), and they lost their sweetness in mono/bridge. But tube amps can be a different story, probably in part because you can change taps to manage the different impedance. Also they won't just "double down" the current & power while straining the PSU and output stage. My VAC switchable mono/stereo tube amps sounds by far the best in mono. 

But @oldhvymec has experience with the MC's, doesn't like bridging them, and that trumps theory. So that's a solid vote against mono/bridging the MC240...

Kevin Hayes discussing his VAC 200 IQ amplifiers With Hifi news.com, 

"With respect to overall power, it's generally been forgotten that very soon after the inception of the KT88, nearly 70 years ago, the GEC/Genalex data sheets showed a 100W/pair operating point in its application circuits' says Kevin. 'In practice, we find that some pairs of KT88s will exceed 100W. The KT88 delivers exceptional sound under these conditions and, in our circuits, average tube life is quite good – typically 6000-8000 hours.'

VAC's custom output transformers are also core to the amp's 'real world' performance. 'In stereo mode the taps are effectively for 2, 4 and 8ohm; in mono, a parallel operating configuration, they are effectively 1, 2 and 4ohm. So, in mono mode [as tested here] the maximum power, lowest distortion, and widest freq. response occur into a 4ohm load on the top tap, which is labelled "4-8".

'Most audiophiles will try more than one tap to see which best suits their loudspeaker (with its varying impedance curve), so we label the taps with a range rather than a single number'.

So it seems in "Mono" (Bridged) mode the amplifiers are seeing 1/2 of the speaker's impedance they encounter when in stereo mode (As almarg described).

Anyway the bottom line is what the listener hears and likes.

Charles 

The Heresy sounds better with tubes, if you want verification go to a Klipsch forum.

 I am wondering why you need to add another amp, you already have more than enough power unless your room is the size of an auditorium. They are a very efficient speaker.

IMO save your money and buy better speakers unless all you listen too is rock. FYI I have Prima Luna and they are very good,the Hersey 4's I own are boxed up in the closet.

Buy what sounds best to you.

Klipsch speakers and McIntosh amps are a fantastic pair. I say go for the MC240 and run them mono. I run my 275's mono and love them.