randy-11, you have some good suggestions above, and I particularly like the Classe suggestions. However, i would like to offer some thoughts for a different approach which is the route that I took over the many years that I lived with MG3A’s; some here will surely disagree with this approach:
There are different ideas on what constitutes "great" sound. For my idea of what "great" sound from Maggies means one needs a tube amp. To my ears Maggies with anything other than the very best solid state amp tend to sound lean and dry; deal breaker for me. Additionally, the ribbon tweeter in the 3 series is ruthlessly revealing of any problems with your amp’s high frequency performance which can cause an audible discontinuity between the tweeter and mid panel. A good tube amp gives the Maggies a sense of fullness and dimensionality of individual images that eludes most "affordable" ss amps as well as tending to have a more "friendly" high frequency character. With a decent tube amp Maggies can produce sound that is remarkably like the sound of live acoustic instruments and voices IF THAT IS YOUR PRIORITY. The downside is that your maximum volume levels MAY be somewhat limited and ultimate bass response and extension will not be on quite the same level as with a good ss amp. This was never a problem for me and while I listen primarily to acoustic jazz and classical I also listen to pop and rock.
When I read you OP, my first thought was, of course, tubes. But, for $1000? No way. I did a search of used offerings here and to my amazement there are two great options that I owned before settling on the Manley 100W monos that I still own. Both are fantastic amps for the money (no affiliation with either seller):
https://www.audiogon.com/listings/tube-quicksilver-mono-el34-2016-12-18-amplifiers-90713-lakewood-cahttps://www.audiogon.com/listings/tube-david-berning-co-ea-2100-stereo-tube-amplifier-2016-12-14-amp...The Berning will give you more output, is fast and is the least "tubey" tube amp that I have ever owned. Because of the design tubes will last a very long time. The Quicksilvers have a midrange and dimensionality to die for (in this price range) and are classics. Don’t let the Quickie’s 60W rating scare you if you listen at moderate volume levels; it is a very solid design. I fully expect some will write that 60-100 watts is not nearly enough for these speakers. It all depends on the size of your room and listening habits. I have a soft spot for the Quickies but the Berning is probably the safer bet with a bit more power....but that Quicksilver midrange! If you can stretch the budget a bit, this would also be a great choice and is what the original owner of my Maggies used for great sound:
https://www.audiogon.com/listings/tube-conrad-johnson-premier-four-100w-ch-tube-power-amplifier-2016...Good luck and Happy New Year!