I'm kinda new to the plannar/magnepan world, but I am really interested in trying out a pair after all the reviews I've been reading. From what I understand these speakers are quite power hungry. What is the minimum I need to properly drive these? 
I currently have a VAC Avatar integrated tube amp. These are the stats:
Type: Integrated vacuum tube amplifier with MM phono stage and home theater (direct power amplifier) mode.
Tube Complement: two 12AX7 low noise (phono), two 12AX7 (line stage), three 12AU7/6189A (power amplifier), and four EL34 (power amplifier)
Options: Remote control for volume (motorized direct control) & mute
Power amplifier ("Home Theater" direct mode):
Output matching: 4 or 8 ohms nominal
Power output: 60 watts/channel ultra-linear; 27 watts/channel triode
Frequency response: 9 Hz - 35 kHz +0 / -0.5 dB, 3 Hz - 71 kHz +0 / -3.0 dB
Power bandwidth: 11 Hz - 63 kHz + 0 / -3.0 db ref. 50 watts
Gain: 25 dB ultra-linear; 23 dB triode
Residual noise: 1.5 mv at 8 ohm output
Channel separation: -72 dB @ 1 kHz; -60 dB @ 10 kHz
Line stage preamplifier:
Gain: 24 dB
Maximum input signal: Infinite (attenuation precedes line stage)
Noise contribution: Approx. 0.1 mv at power amplifier output 
THD contribution: Approx. 0.04% 
Tape output: Unity gain from selector, non-inverting 
Phono stage preamplifier: 
Gain: 37 dB (measured at tape output)
MC phono stage in place of the MM optional 
Residual noise: 3 mv at output (S/N ratio approx. 69 dB) 
Overload: 117 mv @ 1 kHz = 8 volts RMS output, 460 mv @ 10 kHz 
Frequency response: RIAA +/- 0.25 dB 
Notes: Does not invert absolute phase. 

Anyone know if these will do or if I'll have to upgrade? Love the tube sound . . . will I need to go solid state for Maggies? Thanks for putting up with the noobie question :) 
A lot of awesome amp and preamp info!  . . . any suggestions on speaker cables that might be well suited to Maggies? Or is that almost completely up to personal preference? 
cables and their distortion are totally up to you to pick - I suggest very short runs of lamp cord using monoblocks - then blind test some spendy cables (which will produce a reactive load and sound different, maybe not better) - tone controls and EQ, particularly in the digital realm, are the correct ways to alter the sound

both the 3.7s and the 1.7i would be upgrades to the 2.5's 

I just got back from the dealer's place and I can tell you the 3.7i's are a lot better sounding than the 1.7's (and thus the 1.7i's) - I thought vocals were a lot closer than sharp transients like brushes.  Also the larger and taller 3.7's do a better job at being a line source.

at 3x the price they should sound better, eh?

While I could not do blind testing there, the difference was significant and it would be a whale of a placebo effect if it was a visual difference not an aural one.  

I'll do some more listening next week probably.  And there may be a pair of 1.5QRs on the market in the PNW in a month or two...
OK, last follow-up, I promise :)
Anyone here very knowledgeable about Magnepan mods? I've been reading through a LOT of material out there and seen some people invest in upgraded crossover boxes (though not sure those are meant for all Maggie models?) and others invest in fuse bypass. 
Is there any mod that I absolutely should invest in? Any that really make a big difference in these speakers? Thanks!!! 

     Can you give us a rough estimate of what you're willing to budget for:

1. Magnepans( 2.5R, 1.7i, 3.7 or 3.7i)

2. Speaker cables

3. Possible mods to speakers

     Just a range you're willing to pay for each is sufficient.

Maybe a bit late to chime in but for what it's worth - as I do currently have a pair of Maggie 1.7s and am driving with a Rouge Cronus Mag. II integrated tube amp rated at 100W pr. channel. My listening are is about 375 Sq. ft. The 100W Rouge does a very nice job driving the 1.7s at any volume I care to listen to. The stage is very deep, wide and detailed. Not sure if 100W would be quite enough on the 3.7is but does a very nice job on the 1.7s. I think your 60W VAC would do a very nice job on the 2.5 or the 1.7 Maggies but may need more if you ever decided to go with the 3.7is.