Thoughts on choosing an amplifier

After much thinking, too much actually. I have narrowed my amplifier choices down to a Parasound a21+, a Benchmark AHB2, or two Schitt Aegirs. Presently, my modest system is a Pioneer PL 71 turntable with an Ortofon 2M Red cartridge into a Schitt Mani into a NAD C 326BEE feeding Quad 12L Classic monitors. Time for an upgrade, eh? I though I would start with an amp and some more speakers. 

The plan is to remove the jumper on the NAD integrated and use the NAD as a preamp until I choose a preamp to go with the amp. For what it is worth, I am leaning towards a tube preamp - maybe a 6NS7. I also plan to buy a few modestly priced speakers, such as Magneplan LRS,  Zu Omen Dirty Weekend, Bowers & Wilkins 603, GoldenEar Triton Five, KEF LS50, or Warfedale Linton, rather than one more expensive speaker. I like the idea of swapping out speakers for fun, type of music, etc. So I am looking for an amplifier that pairs well with many different types of speakers designs.  Which one of the three amplifiers would you choose?

From reading the forums, people often ask the poster what type of music they like to listen to. My music tastes run from Americana to jazz to opera to classic rock to ambient electronic; mostly Americana and jazz tho.

Thank you in advance for your collective advice. It is very much appreciated.
BigMusic - First time poster
I would recommend reading about the Belles 150A Reference here:

Can’t go wrong with an old Belles amp, lots of power, and a wonderful sound. I was looking for a 150A, but they move fast on the used market, so jump fast on one if the price is right. I finally found an old Belles 400A @ 200wpc, and am very happy with it. Although it was more expensive than any of the 150’s I saw.
Give the NAD M22v2 a look.  It's 300 wpc at 8 ohms.  I use mine with a Herron tube pre-amp and Tannoy DC8Ti speakers, sounds good to my ears.  You can find a used NAD in the $2,500 range.
I'm using an NAD M22v2 amp with an  NAD M10 for streaming. The system is driving 4 ohm Totem Tribe Towers and a pair of Sumiko S.0 subs all with ease. 
I would also submit that the Aegirs would heat up and possibly shut down occasionally as they are not recommended for 4 ohm loads when running as monoblocks.

I've been on an audio journey the last 3 or so years.  I owned the C326BEE, the C356BEE and the C375BEE.(the big let down of the NAD line is the pre amp sections are weak)  Also some Adcom amps and the Parasound P5, after selling the A21 and P7 to start over.  I went through too many speakers from Tannoy, Paradigm and Totem Acoustic to mention.

I will give a vote of confidence to Schiit Audio.  Their stuff isn't just good for the money.  Their Freya+ and Multibit dacs are shockingly excellent sounding period.  I would get you to change up your plan and replace the Nad.

Get a Schiit Freya+ and either the Vidar or Aegir, depending on the speakers you decide on.  You'll be way under the 3000 budget and your ears will thank you.  You'd also need the Mani phono pre.  Or, if you're going to get efficient speakers above 93db or so, the Ragnarok integrated with phono built in would be an option.

The LRS speakers need to be placed at least 3 feet away from any walls.  The LS50 are somewhat bright sounding, depending on speaker cables.  I like your idea of cycling in speakers, it's what I ended up doing.  Any of the speakers on your list could work depending on the provisos I mentioned.  
Any DAC Cherry rated at 200 wpc @ 8 ohms.  The Magnepans won't do much at 100 or 150 wpc.  I looked at the Parasound A21+ for a long time.  I use a DAC Maraschino 60V for my Magnepan DWMs and a DAC 4800A for the MMG mains.  With a tube pre you will be in audio heaven in my opinion.