You'll probably find the combo harsh in the high frequencies. This would be a better option. You would use 4 channels with this amp, not 2.
I owned an Aragon 4004 mk 2 about 20 years ago or so. I doubt you will find it to sound harsh in the high frequencies.
$450 seems like a pretty good price for that amp. I would hook it up and try it out. The main concern with older amps is the capacitors, as they tend to wear out and need to be replaced in about 15-40 years, depending mostly on amp design and amp usage. The hotter an amp runs (Class A bias), or the longer an amp may sit dormant, can shorten the life span of the capacitors.
You should be able to tell by listening to it. If you hear any thumps at turn on/off, or a static like discharging sound while playing, then the caps will probably need replaced. Any local tech should be able to do that for a couple hundred bucks, then you should be good for another couple decades.
If no annoying thumps or crackling sounds, then just relax and enjoy the music. That's a good amp, especially for $450.
"I am mostly interested in the long term reliability and the current value of this amplifier, while $450 is cheap enough for an amp of this caliber is it still a reasonably good buy? "
Its a well made amp and $450 isn't a bad price, I just think you won't be happy with the highs because the 1.6 has an aggressive tweeter. The listing ID didn't show up in my last post, so here it is again.
Its a bit more, but I think its a much better amp for those speakers. Its a 6 channel amp so you can use 4 channels and do a vertical biamp, and is newer than the Aragon.
I bought a used Aragon 4004 MKII amp for $1,000 from a dealer in 1999 and used it, paired with a VTL 2.5 tube preamp, on my Magnepan 2.7qrs for over 15 years. It’s a very good class A/B amp that will deliver 400 watts/channel into the 1.6qr’s 4 ohm load. I agree with jmcgrogan2’s comments earlier, especially about the capacitors. In 2015, some caps in my amp leaked and I decided the $1,000 repair quote was too expensive.
So, I replaced it with a $630 class D audio SDS-440CS amp:
I was pleasantly surprised that this amp significantly outperformed my older Aragon. It had a lower noise floor, more powerful and better controlled bass, better dynamic range along with a similar smooth but detailed mid-range and treble quality. It’s also much smaller and lighter while running cooler and outputting a bit more power with 440 watts/ch @ 4 ohms.
I also agree that $450 is a good price for the Aragon amp and it’s a good match for the Magnepans as long as you’re both aware it’s over 20 yrs old (I believe it came out in 1994) and the caps do have a limited lifespan.
However, for $180 more you’ll get a brand new amp with a year warranty that, based on my experience, significantly outperforms the Aragon,
A word of caution: the class D audio 440CS is very neutral and the overall sound will be mainly determined by the preamp you pair with it: ss for a neutral sound and tubed for a warmer more colored sound. But I know it drives Magnepans well and it’s a true bargain at $630.
Hope this helped,