HI-FI NEWBIE NEEDS HELP!


I am new to the higher end of music listening, actually I haven’t started the listening part yet. I have just purchased an Emotiva XSP-1 pre and a pair of Magnepan 1.7i’s. My listening room is 14x14 but one wall is not closed off completely and there is an additional open space connected that is 8x9. My budget has been unexpectedly diminished more by having to buy new connectors and speakers cables. I just assumed I would be able to use my old RCA connectors and my 50’ spool of speaker wire I bought from Radio Shack 25 years ago. I will pause while you laugh....Anyway, the jist of it is is that I’ve got $2500 left for an amp. I need advice on what would be good for my setup? What would last the next 25 years, as I am a poor man with expensive tastes and will probably not be able to make any further upgrades. Would something used and older be out of date technically in 10-15 years? Could I consider something new that would be adequate for that price point? Should I go mono or two channel? Thank you for your consideration and reply.
widespreadpanic
For a start, odd harmonic distortion present in some systems is more discernible while high levels of even order HD are less offensive.
As far as losing information, let’s assume a straight wire with gain. Now, electronically, consider the hundreds of PN junctions in a digital system compared to a non-digital system. Then the actual ADC/DAC conversion processes? Digital amplifiers? The replication losses changing formats? SMPS power?
If you take a direct to analogue recording and digitize it, you will lose information due to losses inherent in the process. Of course, remastering can add in subtle delays and effects to enhance the sound but it is not the same as the precious original. Again, in other words, once you subject the original signal to interference (pun intended), you lose data.
First, buy a used amp.  You'll get almost twice the value for your money.  There's a highly modified McCormack DNA-0.5 available here now well below your $2500 budget that will last forever and you'll never feel the need to apologize or upgrade.  Another good choice is Bryston -- I'd focus on the SST2 models as I think they're the sweet spot of sound and value (btw there's a 4BSST2 for sale here now near your price range) -- that is also bullet proof and offers a 20-year warranty.  My choice would be the McCormack, but I'd defer to Maggie owners if it's got enough juice to get the most out of your speakers -- although you've got a relatively small room and the 0.5 is conservatively rated so I'd think it'd be fine. 

Second, my opinion is that these amps outclass your preamp -- not that you don't have a decent preamp, it's just that these amps are really good.  And, at least in my experience, the preamp can have an even bigger impact on what you hear than the amp.  Bottom line, at some point you should probably consider upgrading your preamp (or at least audition other preamps in your system) as your speakers and amp will give you even more of what they're capable of.

Lastly, despite what some others have said here, interconnects, speaker, and power cables all make a big and meaningful difference once you reach a certain level.  Whether you need to spend more or less is entirely listener- and/or system-dependent, but at the very least it's more than worth experimenting.  I'd just say this -- buy used and you can usually swap wires in or out at little or no loss.  In fact, I'll throw out an opening salvo.  There's a pair of Acoustic Zen Hologram speaker cables (very good all-around cables) available here now for 500 bucks.  If they don't make a big difference over lamp cord or whatever you're already using, good for you and just sell them.  At least you'll know, for your specific situation, that you're in good shape (obviously you can do the same for interconnects, where I'd recommend AZ Silver Reference series 1 or 2 -- they're both very good).  BTW, by coincidence while researching your question I happened to see this review of your speakers with a Bryston amp and some Acoustic Zen wires -- just FYI.  

https://positive-feedback.com/Issue53/magnepan.htm

Anyway, hope this helps and best of luck in your search!
@willemj 

If measurements are that all-knowing and supersede our hearing ability, then why is there even a market for supertweeters?  Our ears remain the final arbiter.  

Although I appreciate the scientific approach that some here have, I find it laughable that many claim, little, to no difference, in sound, between amplifiers / preamplifiers, not to mention cables, feet, and such. 
Man... would look no further then classe. Great pricing used right now with them newly being purchased by Marantz. If your not comfortable there wouldn’t look past Bryston