Budget amp that will give Magnepan 3.6Rs better depth of soundstage

A used Acurus A 250 is within your price range and will give you at least 250wpc into 8 ohms. But will it be of sufficient quality to get the best out of your Maggies is a question I can't answer.

I agree with misstl, Maggie 3.6s are a lot of speaker for your room. So, making the room ’seem’ bigger acoustically would be the logical first step. That means acoustical panels. They will reduce the level of reflected vs. direct energy and in doing so increase the Critical Distance, that point at which direct and reverberant field levels are the same. My personal preference is Acoustimac for construction quality, fair pricing, and a wide selection of fabric options. Their Home Theater Package 1 would be a great place to start in your room.

Don’t believe that spending more on tweakier panels is money well spent. Inside all of them is either Corning Fiberglas 703/704 or Rock Wool or a paper based material called Eco Core. Rock Wool is the standard works just fine. Much as I believe ceiling panels area Very Good Thing, because Maggies are dipole radiators, I would consider trying 2 of the 6 panels or mounting the bass traps behind the speakers to help control reflections from the back wave.

It’s not so much the watts as it is current and stability at lower impedances. If you have a subwoofer, 100 watts should be more than sufficient.

If you don’t mind an older amp, look for a Proceed HPA-2. it is 250 w/ch at 8 and 500 w/ch at 4 ohms, good down to 2 ohms and will drive virtually anything with a neutral sound and a black background. Know that you will be buying about a 20-yr old amp.

The good news is that its design shares the basic features of dual mono Levinson amps. There are three authorized Levinson service firms that will repair them, if needed, Pyramid Audio in Austin, TX is one of them and does great work, having used them myself. One warning - the amp weighs over 80 lbs. For any needed repairs, however, each of the two amp modules can be separately removed from the case. A local repair firm, technician or Levinson dealer can help with that. They are available used for under $1,000. I have one and it is still going strong. It is a great prescription for any low efficiency, power hungry speaker that requires high current.

Too much speaker for too little a room.  Knock out a couple of walls.