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 Would something used and older be out of date technically in 10-15 years?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
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 
Always an interesting argument, paper graphs vs. ears. I have sold high end audio and had a company selling and installing high end systems. The brands I have sold or were the dealer for were JMLab/Focal, B&W, Maggies, SoundLab, Ayre, AudioResearch, Acurus, Aragon, YBL, Wadia, PS Audio, NAD, Rotel, PSB, Harbeth, HSU subs and quite a few others. I also have an Associates Degree in Electronics so I can understand a lot of how circuits work. And I can solder. A lot of theoretical Engineers can't. My point is, I have heard and compared a lot of different brands and models for a living, and I liked my job. I have made my own interconnects and since a lot of my systems were in-ceiling/in-wall stuff I even bought 15 different volume knobs and tested them. BTW, Knoll's resistor based knobs sounded the best, way better than pots.

So yes, Virginia, there is a difference in amplifiers. I sought different audio gear and interconnects because of their differences. Because people hear and gravitate towards a particular sound/flavor. That's why there's not one generic box that says AMP on it for everybody. I think all of the brands I sold were quality, but they did sound different. Probably because I played shred guitar for years I like the sound of tubes. On paper they may not spec well, but the most sound I've gotten out of paper was shaking it. There are a lot of fraudulent or misguided attempts to enhance sound quality but I've seen some weird tricks that work. One is big ass AC cords-12ga. high strand count cable with hospital (Watt-style) connectors. After running the electricity through miles of Romex why do they make a difference in the sound through speakers? Doesn't work on some systems but my AR LS-8 and Aragon 8008BB appreciated them. Personally I really liked the Aragon amps, especially the 8008 series. And yes, they sound great with a non-balanced pre. I like tube pres myself, but that's just me. 

So my job was to listen and compare and then present my recommendations to the customer based on qualifying questions like their existing gear, room environment, tastes in music and so on. If you do something for 20 years you should get good at it. And for every customer I had to prove to them there was a difference, an improvement or no sale. Depending on reviews only sucks, I trust my ears to know what's good (for me, anyway).

To wrap up a long-winded conversation: if you can find a high end shop near you and if they're a 'good' shop they'll work with you. Sometimes audio repair shops will carry used and consignment gear. If not check out reviews from good audio mags like Stereophile (I hope they're still around) or the like. CNET ain't gonna cut it for good audio but I do like their TV reviews (I'm ISF trained). Manufacturers sites usually archive reviews on older models as well.

You are going to get a lot of recommendations. Opinions are like... bellybuttons... (polite version), everyone's got one. Since this is a long term purchase take your time. Join an audio-enthusiast club if there's one nearby or post a c-list ad in 'electronics' and start your own. I used to attend monthly meetings at members houses to hear their systems, listen to mostly good music and geek out about sound and motorcycles (lot of members also rode). Enjoy the hunt, most of the above recommendations are good ones.  
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IMO the scientific audiophiles among us seemed to have missed an essential point in relying on low distortion or measures of human hearing.  The goal, ultimately, is not accuracy.   Accurate reproduction is impossible.  Reproduction of what?  The instruments?  The engineers’ concept of the bands sound?  The microphone manufacturers concept?
it seems to me what many if not most of us are seeking is the maximum satisfaction with the sound of a system we’ve chosen and assembled with any and all of the elements we deem effective. 
This may or may not coincide with ‘accuracy’.  Whether it does is irrelevant to anyone but the individual audiophile. 
In 40 years I have never heard two major components that sounded identical.  To me.  
Btw. I’ve blind demo’d ic’s and speaker wire for many friends and not had a single one fail to hear some difference... which they preferred...now that’s something else entirely.