Maybe a Butler TDB-2250? Go to ButlerAudio.com for more info...
Rockport uses Gryphon Class-A amps (I'm sure among others) when voicing their speakers, but they may be out of your price range. However, considering that along with the sound characteristics you're looking for another Class-A amp might be just the ticket. I think something from Clayton Audio would be a great match, or maybe a used Plinius SA-103 or Pass Labs amp. Just make sure whatever amp you get has enough power to allow the Miras to open up to their fullest. You might ask Rockport for recommendations as well. Best of luck.
I would recommend either the 100 wpc Lamm M1.1 (full Class A) or the 200 wpc Lamm M2.1 (Class A/B albeit heavily biased into Class A), monoblocks - I own the latter btw. Both have a single 6922 tube so both amps have a nice touch of tube sound. (And with only one tube in each amp, tube rolling is relatively cheap and easy.) Both amps have rock solid bass response and a lovely mid-range. FYI: Both are just a touch dark soinding. Used they run around $6-7K.
I should also point out that both are no longer in production, although their successors are, the M1.2 & M2.2. My friend uses the M2.2 with his Rockport Antares. However both of these cost around $8-10K used.
My two cents worth anyway.
Can kinda sorta help. I heard Ankaa's driven by an ARC Classic 60. The preamp was a Shindo. CD player was AA Capitole Classic. I was wanting for VERY little, and I'm not a digital guy. I really thought that particular ARC amp w/ the Shindo pre sounded great. Haven't heard the Mira's, but Andy couldn't make a bad speaker. Congrats on your Mira's.