Nad M33 or something better

The m33 is very good quality  and should work well with the KEFs. 
 

It would help to know what aspect of the sound you are not happy with?

I think the bass could be better and I don't know if that is a speaker issue or the NAD?

I most strongly doubt it’s the amp. Kef R3 have pretty good bass for their size and the m33 should be able to drive them to their max, but most any smaller monitor speaker can benefit by properly adding a subwoofer or two. In general larger rooms will always require larger speakers overall to deliver good quality full range bass. Subwoofers help achieve that, especially with smaller speakers.

I agree with @mapman. I would look at adding a subwoofer. 

Hey guys thanks for all the suggestions. As a matter of fact, I added a Kef KC62 sub yesterday. It made a nice improvement but stills needs some adjustments. I'm hoping this will solve the issue.

Thanks to all. 

Nice! Good choice on the sub!

I’m sure you will end up in a better place this way, but the key is to get teh sub dialed in just right. A good sound meter app like decibel on Iphone along with some streamed white noise as a reference signal can get teh job done fairly well.

FWIW I have KEF ls50metas and use a sub with those in a smaller room. I tune in the sub using the tools mentioned above and this makes a large very clear and noticeable difference. I do not use an active crossover to limit low end going to the mains, which would probably take things to an even higher level, but the results as is is still quite good. R3s are a step above ls50s in terms of their inherent ability to go loud (say above upper 80s db in a modest sized room) with low distortion, but playing things that loud is never good for your ears regardless so always be careful there.

Good luck!.

hegels are used by kef at shows, and i would suggest they do this for good reason, sonically....

+1 @jjss49  I was going to suggest checking out the Hegel integrated amps.  They have a very high damping factor which matters to some speakers esp. in bass reproduction.  Hegel is a relative good bang for the buck.  Not sure how many hours you have on your lovely KEFs but speakers will have more bass presence after they are fully run in.  Enjoy and Cheers

Hegel gets a lot of love here these days but it’s far from the only fish in the sea and not without its own unique flaws, at least in some cases from what I read, mainly with the digital implementation and overall comparative value.

If you do some homework the m33 looks very good in both regards. I have auditioned m33 and my findings to date are consistent with what I read.

I was going to go with an m33 about 2 years ago but ended up trying a Cambridge Evo 150 first, which saved me a nice chunk of change. The m33 would still be a reasonable step up in terms of overall drive capability but I decided I didn’t need the room correction capabilities at this time and the Cambridge offered usb input out of the can which I needed at the time and came in for $2.5K less.

+1 to the add sub consensus 

Great comments guys.

Thanks for all the input..

That is a nice set of speakers! I have the LS50's and love the sound of them, I am guessing the Ref 3's are spectacular. Having gone through some upgrades in amplification with my KEF's, I would say that you could find some significant improvements trying some other gear. My original amp was an NAD 375BEE integrated which sounded great and provided a deep well of power for the low sensitivity LS50's. My eyes opened up when I bypassed the preamp section of the NAD integrated with a Schiit Freya+, it was a significant improvement. I later replaced the amplifier with a Coda #8, again a very significant improvement.

I am not advocating for these products, and in fact I am in the process of auditioning replacements for the Freya, but just saying that I think you can do better with a speaker of that quality. The M33 looks great on paper, but like every Swiss army knife solution, I expect there were compromises made along the way. The fact that you are not getting the bass you want, and you are still missing that certain something tells me you should shop around.