I feel it is time to upgrade my 1977 system.......

@OP - What model is your Music Hall Turntable. If it's one of the more budget offerings, you should include a Turntable / Arm / Cardridge upgrade.

As regards amplification, a high quality integrated is more than sufficient for your speakers given their efficiency. Passlabs has been mentioned and is excellent.

I'm not sure of Copland from Denmark is distributed in the US but they make excellent integrated amps.

Prima Luna has also been mentioned and is a good choice in Tube amplification.

If you are using old cables with your system currently, be sure to put aside part of your budget for decent cables. The list is endless, but in terms of widely available cables, Audioquest do a very good job.

@charles1dad

I acquired the Franks about a month ago and the Music Reference RM9 MKII has been sold to a good home. The Franks have proven to be a better match for the Altec’s, as they allow me to hear deeper into the music.

@curtdr wrote:

"If you're intent on keeping the Altecs, OK... but speakers too have come a long way for the money.  If you like lively and yet with that "audiophile classy sound" and old-school looks: Klipsch Forte IV.  aprox $5000"

My Model 19's superseded Harbeth 40.2 Anniversaries and Dynaudio Confidence C4's and I can say without reservation that I get more enjoyment from my 45 year old refurbished Altec's than the well regarded Harbeth's and Dynaudio's... so one should not assume that newer speakers are better or more enjoyable that classic vintage speakers.  If the OP is satisfied with his vintage speakers, I would not replace them with something newer without validating  first hand that newer is automatically better.

@pdreher I agree for the most part and myself I own and love Epi 100 speakers and their little brothers Epi 50, with some updated parts from Human Speakers.

So, as I don’t know the Altecs in question, I don’t necessarily assume that new speakers are "better" than those... though I’ll note that even you have refurbished Altecs.

However, that said, speakers, like amps, have come a long way in "bang for the buck" since the 70’s, especially when you factor inflation, and there are some relatively inexpensive, $2000-5000 range, choices that perform at an astounding level that only the very, very best from "back in the day" could aspire to. Think about the updates over time to the JBL 100, the KLH 5, and the Klipsch Heritage... There are also far more choices in even less expensive "budget" speakers these days that only a select few from the 70s could come close and that only if updated.

I have Altec Flamencos and recently asked for some advice on amplifiers that you might find helpful. Coincident Frankensteins and Music Reference were recommended for my speakers as well. Also Atmasphere thought that his class d monoblock amps worked well with his similar high efficiency speakers and should be a good pairing for the Altecs. 

 @alexberger gave me the following useful info regarding amplifiers and crossovers:

" I have experience with Altec 604E that has similar sensitivity to Altec 846A. In the mid size rooms that I had 200-300 sq feet, 300B SET has enough power. I used McIntosh MC30 monoblocks (30+ watt), Marantz 8B in triode mode (20 watt), and 300B SET (6-7 watt). I also heard 2a3 Boothed monoblocks with my speakers and they were good enough in terms of power. The 30 watt McIntosh MC30 sounded great with my Spendor 2/3 speakers but with super sensitive Altecs it sounded rough and not as natural and refined as a 300B amplifier. 
What is really important is that for a 300B amplifier it has to have a powerful driver tube like 6f6, 6v6 but not popular but weak 6sn7.
The strong power supply with a big and good quality capacitor.
If your room is not huge, I suggest you try Coincident Frankenstein 300b monoblocks or Aric Audio Super 300B SET. Both these amplifiers have powerful driver tubes, interstage transformers and good power supply.

There are a lot of information about crossovers for Altec on Jeff Day page. Jeff prefers Hiraga schematic crossover for his Altec speakers.

https://jeffsplace.positive-feedback.com/

https://jeffsplace.positive-feedback.com/%e2%99%ab-vott-system/