Hi John,
There are a lot of factors involved but I would have thought there was nothing to gain by moving from the Sunfire to the XPR-2. The Revels are 87.5dB/1w/1m efficiency and 6.5 Ohms (nominal) with a 3.5 Ohms minimum rating. That should not make them especially hard to drive and 200 watts from the Sunfire amp should be more than enough, unless you have a huge room and sit a long way back from the speakers and demand very high (100+dB) peak SPLs. The very comprehensive user manual for the Revels seems not to contain a word about their power handling capacity but with an efficiency of 87.5dB and a 200 watt input you should be able to hit about 105dB if you sit 12 feet away (actually that calculation is based on an 8ohm speaker so you could do even better than that). Of course that leaves you no headroom and to get 3dB headroom you'd need a 400 watt amp. But can the speakers handle 400 watts? If they can’t then there is no real point to having one - extra headroom is always desirable but if the speakers can only handle a genuine 200 watts, then you can’t do much more. I am not talking about the manufacturer's spec which will be continuous RMS watts and not very meaningful but real-world power handling, Absent information from Revel it is hard to know. Perhaps you have this info from another source - a review maybe?
If indeed you are driving the Sunfires into clipping, which seems unlikely on the face of it, then the 600 watts of the XPR-2 could be beneficial, providing an additional 4.5dB of headroom.
My question would be - what makes you believe the speakers need more power than 200 watts? And can the Revels handle more power?
Given that you say your room is "terrible acoustically" and given that the room has far, far more influence on the sound than any amplifier, you may be wasting your money bu buying a new amplifier, if the problem you feel exists is with the room. It would help draw more constructive replies if you could in some quantify what you mean by being "not happy with how the Sunfire is matching up".
Do you have a SPL meter? If so, can you play something at your normal listening level and tell us what the SPL reading is at your usual listening position? This will give us a big clue as to how many of the Sunfire's watts you are currently using. (If you don't have an SPL meter, download a free smartphone app - it will probably be accurate enough for this purpose. Better still, download two and compare them).
There is a danger you could drop a lot of money on an amp and it still won’t solve your problem because the problem isn't a lack of watts. Emotiva amps are terrific (I own 4) and they are great value for money - but they still cost a fair few dollars!.
The fact that Audyssey has found the F3 of your speakers at 250Hz demonstrates that something is wrong. Audyssey is pretty good at finding the F3 in-room response of speakers. Assuming the Audyssey mic isn't faulty and that you used the correct measuring technique (see the Audyssey 101 linked in my sig for more info) there is a reason why Audyssey is believing your speakers can only handle down to 250Hz! There has been a recent case of a similar experience reported in the Audyssey thread and the problem was solved by using some reflection absorption behind the listening position (rear wall) for example. The more you tell, the more convinced I am becoming that swapping the amps out would bring you little benefit. Fortunately, if you wanted to just suck it and see, Emo let you try their amps at home for 30 days and all it will cost you is return carriage.
It's not so much the size of the room that is important but more how far you sit from the speakers. What is your distance from the speakers when listening normally?
If the speakers are showing distortion and it is a result of the amp, then the amp must be clipping (assuming it is not broken). The only way to know if the amp is clipping, without measuring gear, is to calculate the power it is being asked to deliver and for that we need to know the SPL you are listening at and the seating distance. Experience suggests that it is unlikely you are clipping the Sunfire, although it is possible. If you provide the information I asked for, we can work it out and see.
The Emotiva will absolutely, definitely, without question NOT be a "better sounding amp" than the Sunfire, or vice-versa. Both makes exhibit no audible distortions when working within their rated specs and there is nothing really in their specs that would make one believe that either amp will do anything other than take the input signal and output it entirely unchanged, other than in amplitude. The sole difference between them that could be important is that one allows for 4.5dB more headroom than the other. If you are running the Sunfire into clipping, then more power will solve that problem (so long as the speakers can handle it) - but I would be really surprised if you are clipping a good quality 200 watt amp.
I don't think you will get any comments on the XPR-2 simply because nobody here seems to yet own one. All we can tell you is that Emotiva have a very good reputation for selling very good amps at very good prices. I see no reason to believe the XPR-2 would be any different. But no matter how good it is, if you are not clipping the Sunfire, then you will hear zero difference from the XPR-2 and will have wasted money you could have spent elsewhere to better effect.
I think you are on the right lines by rethinking things. I am sure that the Emo and Sunfire will sound essentially identical because there is no reason to believe they won't. I have checked the specs of both and they both perform well within the audible limits of distortion (as one would expect of a decent quality SS amp these days). They both will essentially take an input signal and reproduce it without adding anything or subtracting anything, or doing anything audible to it other than make it louder.
I believe that the problems lie in the room itself, so far as I can put together the clues in your various posts. And Audyssey finding the F3 at 250Hz tends to confirm this. If Audyssey is working as it should and it believes that you are 3dB down at 250Hz, it is easy to see why you feel you are lacking in bass! What sub are you using? You have a very, very good unit in the Marantz, very good speakers and a very good amp, so something is clearly not right as you should be experiencing a very satisfying sound. You are crossing over to the sub at 80Hz so that shouldn’t be a problem based on the spec of the Revels.
How have you set about integrating the sub into the system? Normally I'd say to just use Audyssey and let that do its work and be done with it but something is causing Audyssey to flunk out and, so far, we don't know what it is. Do you have a SPL meter? If so, then play the test tones from the Marantz from the MLP and see what levels the speakers and subs are reporting. You can use a free smartphone app for this as all we are doing is trying to get a rough idea. They should all be playing at 75dB. The sub may report as much as 5dB less than this due to inaccuracies in the SPL meter at the LF end. If all the speakers are reporting roughly 75dB and the sub is roughly 70dB, then probably things are set up OK wrt to SPLs. If not, make a note of the various trim settings first (so you can go back if necessary) and then adjust the trims so they all read 75dB. You'll have to use some judgement for the bass, but all we are trying to do here is get a rough idea of what is going on - for example if your mains are reading 85dB and your sub is reading 55dB, we have found the problem with no more work. But this is unlikely.
Are you able, temporarily, to move the speakers to a more suitable location, just so we can do some listening tests? If so I’d advise doing this and if the result is massively better then we know that it is the speaker placement that is the problem. Below about 400Hz you are really hearing much more of the room than you are of the speakers, and as it is the bass you have issues with, this is why I suspect placement problems. The room is the most influential factor at the bass end and speaker and sub placement is the next most influential factor. If you can put the speakers against one wall, suitably spaced, a couple of feet from the wall if possible, and try the sub in one of the front corners and/or somewhere between the speakers. If you are able to do a sub crawl first then this would be even better! If after all that, the system sounds as good as it should sound then at least you know what the problem is and you will also have saved yourself several hundred bucks on a new amp that will never fix a problem with the room. Incidentally, it might be worth re-running Audyssey with the speakers in this configuration/position and see if it now properly reports the F3. If it does, it will also set the distance and levels correctly and you will be surprise how very good XT32 is!
Can you do a rough to-scale sketch of your room showing where the furniture is, where the speakers and sub are, where the openings, windows, doorways etc are and so on? Nothing fancy - just a freehand drawing will do, with dimensions please. If you can scan this and upload it here, it will give me more info to go on and perhaps enable me to suggest more things you can try.
If you can do all of the above and then report back with your findings we can continue the troubleshooting. Whatever happens you will almost certainly need to have some form of EQ on the sub - Audyssey XT32 does a marvellous job of EQing the bass so normally I'd just suggest using that, but there are alternatives and we may need to consider them later depending on what your experiments show.
Don't give up - you have the makings of a great system - all you need to do is get it working as it should!
EDIT: you could also be sitting in a huge null. Temporarily relocating the speakers/sub should give us some clues there. But before you do anything, play something bass-heavy and move around the room. Is there a place where the bass suddenly sounds good?
The distortion ratings don't mean anything once the distortion levels are beneath the point of audibility. This is common for all modern SS amps that I have ever seen specs for.
I was only referencing SS amps wrt to distortion. I think the main point is that you say "it does not mean this will be audible". If it isn't audible then it doesn’t matter and we can ignore it. Theoretically an amp that has distortion of, say, 0.01% is ten times better than an amp that has distortion of 0.1%. But as neither amounts of distortion is audible, the first amp performs no better in reality than the second amp. That's really what I was meaning. Of course, marketing departments may choose to try to convince us otherwise ;)
I am not familiar with the 818, but my older Onkyo 5007 had this weird sort of trigger arrangement. The only way to get it work the way you want it to work was like this (you do need a programmable remote though, like my Harmony):
