I would try the Luxman, I bet you will keep it.
Return shipping Cost: it’s no loss, if you keep it, you have to send them the McIntosh. Keep the McIntosh, return the Luxman, Soooo it isn’t any more cost to try it.
I’ve got a Luxman, 10 wpc tube amp in my Office System. My 1st and only Luxman. Except for price, I wholeheartedly recommend it, and, over time, you forget the price. You are simply not aware of it, just the wonderful involving music.
It has built in MM/MC Phono, I’m using it’s MM with my AT440ml MM cartridge, also quite happy with that part of it. Just to say, I’m happy with all aspects of my Luxman.
https://www.luxman.com/product/detail.php?id=33
https://www.stereophile.com/content/luxman-sq-n150-integrated-amplifier
Now playing my restored AR-2ax, sensitivity 91.5.
https://stereonomono.blogspot.com/2014/05/acoustic-research-ar-2ax.html
Previously played the least efficient 87db speakers I own, Wharfedale Diamond 225.
https://www.wharfedale.co.uk/diamond-225/
As reviewers say, it seems to have plenty of reserve power, yes it does, it drove the inefficient Wharfedale’s with more volume than I want/need. Perhaps ’extra power’ is true of the Luxman you are considering, I suspect so.
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I had McIntosh Mc2250 SS 250 wpc in main system when I was using my JSE Infinite Slope Model II’s, 4 way sensitivity 90db. I played with more volume in that larger space, and my current at the time 30 wpc tube amps seemed underpowered. I have to agree, it was more like a muscle car, impressive, yet not as invisibly involving.
I went back to highly efficient horns/15" woofer and switched back to tubes, sold the MC2250, don’t miss it one bit.
IF the Luxman had 16 ohm taps, like my Cayin A88T does (22 or 45 wpc) I am sure the Luxman could drive my main system wonderfully. Cayin is also invisibly involving, which is simply magic when that quality exists.