Options to upgrade from Cambridge Integrated

I second the Audio Refinement Complete. I like it better than the NAD integrateds (and I like the NADs better than the Cambridge amps). Others to consider would be solid-state amps from Creek and Rega.

I would also consider inverting the priorities and spending a little more on the amp and less for the speakers. That might get you into tube amp territory. Audio Space (from Hong Kong) make very nice tube integrateds.

I would not consider electronic separates unless I were spending over $2K. There are just too many good integrateds in that range.

I agree with Ehart when he says the AR is smoother and less forward than the Cambridge. I don't think you have to go with separates to better any of the integrated amps he lists. I think there are other integrated amps--Qinpu, Vecteur, SimAudio, perhaps Bryston and Creek too--that will outdo any of them and sound better than any similarly-priced separates. (That's without even looking at tubes.) Those amps are all more pricey than you want, though.

I think Ehart has another point when he says a $500 integrated may not give you a big enough step up to be worthwhile. We're not trying to drive your costs up here, but a too-small step can wind up more expensive than a big one in the long run.

Ehart and I do seem to have a different take on the relative importance of speakers and amp, and certainly there may be good reasons for going either way. If I were you I guess I would do just as you are doing--replace the speakers first, since they are the weakest element in the chain just now. After you get used to your new speakers, you may find you have a better idea of exactly what you want in an amplifier. The search will likely be a lot easier (although not necessarily less expensive) once you know that.

Nice to have the update!

Your new listening room dimensions have indeed changed the equation. You are not looking at steadily improving your present system any more, starting with speakers (the weakest element right now) and later changing the amp. This is because neither your present speakers nor your amp is well-suited to a large room. If you want to try to match your system to the new room, you will need to take a big step.

My take would be this: unless you plan to listen nearfield (and forgo the "room-filling sound" experience), you will need speakers that can move a lot of air. That means forget monitors, you need big woofers, or multiple woofers. Such speakers need muscle unless they are very efficient, and muscle costs.

Speakers with an efficiency rating under 88 dB will need a big amp, at least 150 wpc if solid-state and about half that if tubed. If you can find a speaker you like with a 90 dB rating you can cut your required amplifier power in half. That's a lot less money, and often better sound, since IME the smaller amps take less engineering and fewer exotic parts to sound good.

My first notion would be to listen to one of the Triangle floorstanders. (I would be tempted to say, the bigger the better!) These are efficient speakers with terrific imaging, very lively and fast and not terribly costly for their quality. Their sweetness depends on what's upstream of them, though, and tubes are a good bet here. Another good bet speaker-wise would be Reference 3A, but these are more costly than Triangles. There are sure to be other efficient larger speakers I can't think of right now.

Vandersteens are not the worst idea with your current amp but I agree that this setup will sound meek, even a bit lost, in your new space. However a budget revision, upwards, may not be feasible under the circumstances.