Im about 12 feet from front L&R&Sub. No EQ. The only setting on is whatever the mic found for room correction. Sub is crossed at 80hz. but speakers are set to Large (even when set to Small they handle just a tad more). I use to almost bring this receiver to the max with the def techs, lets say to 95 on the volume with no problem and they were more sensitive, but they do have built in subs to crossover low frequencies.. now I cant go past 74 to 80 without the KEFs sounding like they cant handle it. But again, Im not sure if its the speakers or receiver. The sound is so good on the KEFs that I dont mind if the KEFs cant handle bass or loud volumes this much, but just want to make sure they don't need to be serviced or not or if the receiver cant keep up. I listen to all types of music.. but the ones that I'm having a problem with at loud volumes is more like house, dance, and heavy metal music.
Something does not sound right. You said 95 on the volume, but what is the maximum volume setting? I guess it may be 98, but even if it is 100, you should be no where near 95!! What is your signal source, CD player, DAC?
The R700s are rated 89 dB/2.83V/m, 8 ohm nominal, 3.2 ohm minimum. Nominal is almost meaningless, so let's be conservative and de-rate the R700 to say 83 dB/1W/m, in order to use the calculator linked below:
http://myhometheater.homestead.com/splcalculator.html
According to this online peak spl calculator, you should be able to get almost 98 dB of peak spl from your listening position. If you do listen to sustained 85 dB level, that few people do, you still have 12-13 dB on hand to cover the peaks for most music genres, definitely the dance and heavy metal music you mentioned you had problem with.
Since you listen to those type of music (that are relatively compressed) at such high spl level, you may want to add a fan or two to keep the expensive Arcam cool so it can live longer.
Before you go and get an amp, you may want to try doing a factory reset on the Arcam first in case some settings were messed up, causing the problem.
Also, double check that the binding post shorting links at the back of the R700s are perfectly tight, to make sure all the drivers are 100% engaged. Those links have been known to loosen up, or not tightened properly for whatever reasons.
One last thing to try if you haven't yet, is to use a CD player for input. That's just to rule out if your source signal is too low. I know that is unlikely the reason, but just want to cover all bases.
I can tell you that my Denon AVR can drive the R900s easily. It is true that the R900 is a touch easier to drive and my AVR is a touch more powerful than yours, but still, there is no need for me to turn the volume pass even -10 (-79.5 to +18) in the relative scale, or 70 on the absolute scale (0 to 98) regardless of which source players I use.
After all the double checking are done, if you insist on getting an amp, get one that is returnable without penalty as
I am not sure exactly what the Arcam's specified:
"Preamplifier outputs Nominal output level 1V RMS" really mean.
Hopefully it is capable of much higher than 1 V rms without clipping, but we don't know for sure.
The suggested Crown XLS 1502 is a safe bet because it has a high input sensitivity of 0.775V that you can select, and still enjoy a decent SN ratio of 97.