I guess my setup isn't far off where you intend to go or could go. I had a 506/501 front end to my power amp and A2s. I still have the 506 & 501 in a second system but I'm using a SqueezeBox into a 568.2MM now in my main system. Rather than buy a 501 or 502, you'd probably get the bet result for your money by locating a 568 or 568.2MM (depending on budget) as they function as preamp and decent 24-bit DAC is one unit. My A2s have a little bass assistance from an M1500 sub, and here the 568 again has an advantage over Meridians analogue preamps in that it has bass management that enables excellent integration. The A2s are quite easy to drive but respond very well to amps that an deliver plenty of clean power. A 557 should would do a good job, and a 568 has balanced outputs so you would not need a 502. 565 would probably e reasonable alternative is you can find one significantly cheaper than a 568.

1: DSP5200SL, Reviver, 598DP, 568.2MM, 504, SqueezeLite/RaspberryPi2 via Explorer, Furutech FP-SWS-D and power cables
2: Argent 2, M1500, 506.24, 501, SqueezeBox 3, Electrocompaniet AW-120DMB, Nordost and VdH cables
Streaming: Mac Mini server with Logitech Media Server to SqueezeBox 3 (4 systems 16/44) or SqueezeLite (for 24/96)