In the under $2500 category, diminishing returns?


In the less than $2500 (new/used) category for integrated amps, is there a point of diminishing returns?

Here's my situation, I'd like to set up a system around a pair of Maggies (MMG) I already have. One source will be my iMac with a Music Streamer DAC. I'll likely have a modest turntable soon too (Rega RP-1). I listen to a wide variety of things, but let's just say... Radiohead
I can budget upto $2500 for an amp, but would love to spend much less than that and sink the rest into CDs and vinyl.
An NAD C 326BEE can be had for around $4-500. A Music Fidelity A5 (used) for about $1500. Would there be a 3x difference between the two? Can I get a significant upgrade in sound by spending the whole $2500? I'd like to hear your thoughts.
adnan
Room size and listening level should be considered. The A5 is around 200wpc and the NAD is around 50 I think? I've never owned the MMG's so I don't know how much power they need?
If you are planning on keeping it for several years I would say go for the better amp. Yes the A5 is a better amp. I believe it's worth the extra dollars. But hey I like spending money!
I have MMG's,thought they sounded good with 50 watt amp.remember they are 4 ohms.
But discovered 100 a side was better and 200 even better.
Now use a rebuilt,modded Hafler 500 putting a measured 524 watts a channel into 4 ohms and they sound great !

Maggies need juice,the more the better.IMHO more power is preferable to a better amp,of course one wants both-LOL .
For bellow a $1k Aragon 8008 300Wpc will drive'em near perfect. The rest of budget you can get sub and dive into nirvana.