The amp sounds pretty nice, but the tuner is kinda kneecapped by a response limited to 20Hz-15kHz compared to the amp's roll-off at 35kHz. That gives a serious audible difference between different sections of the receiver. Also, the noise rejection is only ok, so you get more static and fewer channels than a really good tuner.
I got the mac 1900 because I wanted it to be a one box solution that sounds just like the mcintosh separates units that I love (moody knows what I mean). To that effect, I had mixed results. It has the superlative build quality I have come to expect, but after listening and doing some more research, I figured out why it didn't quite meet my (really high, basically stratospheric) hopes. I think they used the front end from the mr-73 tuner, c-24 preamp board, and mc 250 outputs. Those are all good parts, but a few generations yet from their best work. I was comparing it to the MR-78 - C-32 - mc2125. It was never going to win, except in compactness. To be fair, even the MR-78 isn't as good as it can be without a few mods. It rolls off way too low, but I digress.
It might sound like I'm saying it wasn't good. I'm not. I really liked how it sounded (except on fm), but there are a few better receivers out there (and a few in my house haha). I wanted it to have the cajones to put out the deep bass (10-30 hz), but it wasn't quite viscerally there. I wanted the fm to have a higher roll-off. The human ear goes to 20kHz, so anything under that really is noticeable. Great tuners sample at 39kHz and you can really tell when you hear it.
For what I paid for mine, I'm happy with how it sounds. I'm glad you like yours. McIntosh is a great brand that is hard to go wrong with in the vintage realm. I think every vintage McIntosh is always worth fixing. I can't really say that for any other brand.
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Just as a quick addition, I've only found two receivers ever that sound as good as a McIntosh separates system, but they are power limited and have their own drawbacks. I hope my sx-1980 will join their ranks after it comes back from its restoration.