In the under $2500 category, diminishing returns?

Having owned/tried pretty much every integrated under $4K, I've learned that diminishing returns don't really start to kick in until about $3k (new list price). But you have to double the price to get 'a lot' more. A $2k is way better than $1k, $3k is way better than $2k.

That being said, there are tons of choices and system matching is very important. Don't be afraid to spend the money to get what you want, just take the time to listen and decide for yourself.

Personally, quality is always better than quantity (power) if you can't have both. Most high quality integrated amps under $3k run with 50-100 wpc, which is fine for most uses and should be fine for your Maggies. If you are looking at tons of power, expect to give up on quality at this price point.

Forgot about integrated.
Once you get introduced to W4S STI500, you'll realize that diminishing returns are almost at its best right there.

I've owned Maggies for over 20 years ,they will not do anything like their best at 50-100 watts.
The best I've heard MMG's sound,all things cosidered , is with Belles Amps,with a 150 as a minimum.
Personally I'd find the cheapest used Belle putting ot 300 watts into 4 ohms,buy that and not look back.

Since your budget is $2500 a Bada Purer 3.3se has plenty of power and current for the MMG. I know it's a BAT 300k clone but it sells for around $1200(new)at Pacific Valve. This gives you $1300 for a turntable-cartridge and phono-pre. Consider a new budget Thorens table over a Rega due to better build quality.