Can't decide on Integrated Amp - Please Help

Hi, really trying to find the best deal I can on a used integrated amp. My current set up is

Monitor Audio RX6 speakers
Oppo 105

Looking for a strong integrated that if I wish to upgrade my speakers will easily handle the change.

Looking at spending no more than $3,000 for a used example and would love some help. I stream most of my music through the Oppo instead of CD's and listen to a lot of Pink Floyd, Dave Matthews, Sting etc

Few choices i have outlined and really hard to be able to audition anything and would like it to match the speakers and Oppo well

Rega Elicit - R
Krell S550i
Hegel 200 or 300 if can afford (is the DAC much better than the 105)
Stello ai500
Saw a PLINIUS HAUTONGA Intergrated A but don't know too much about company.
Modwright 200

My room is around 15 x 15 with wood floors

Thanks in advance for help
The Harman/Kardon 990 amp has gotten very good reviews and has a terrific amp section (VERY high current capability), can handle up to 2 subwoofers, plus it has room correction capabilities - very sweet! And it's $1995 brand new. Definitely check this one out...

If you are not opposed to Tubes you might want to try an ARC VSi-60. At the moment there are a couple for sale here on this site; no affiliation.
Another great SS Integrated although you would have to bump up your budget a bit(used) is the Pass INT 150 or 30A. Reno Hi-Fi offers a free 10 day in home trial all you pay is shipping to and fro if you send it back.

Another possibility would be the conrad-johnson CA200. I own one so therefore I'm prejudiced but it did replace some more costly separates (also conrad-johnson) and I've been very pleased. There are a few available now on Audiogon within your budget. I'm not familiar with your speakers but I do have an Oppo 105D which I use almost exclusively with either external hard drives or solid state drives. so that's a common point of reference. I find the CA200 to be an excellent match with the rest of my system and it has simplified my life.

Just a thought.