I will take a shot--it is 4:14 a.m. and I have to take my daughter to the bus for ski school soon, so I have some time to kill and I can make a few suggestions.
First, I note what you are looking for--deeper bass and a more upfront presentation. With that in mind, and keeping in mind the speakers you have (nice ones, BTW), for me it is easy to eliminate three of your options. Now, I can understand wanting to improve your system--the Yamaha integrated is more "polite" sounding than anything else. Yamaha doesn't want to offend anyone, so the sound of their integrateds are pretty bland. Integrateds are not where Yamaha has made its mark in the world.
Unfortunately, the same is true for the Marantz integrated. I have auditioned that unit on several occasions (looking to improve the stereo in my study) and I found it bland beyong words. I researched it and found that it has almost a pure Class B amplification circuitry. Lacks warmth and is kind of dull sounding. I have not been impressed with their CD player, either. It's good, but nothing special.
The Cambridge is a very nice unit--has that nice British amp warmth that I like very much. However, although a very good unit, it does have a rolled off top end that is also a bit laid back. Not the more up-front treble you are looking for. Now, I have recommended this unit to several people, but based upon what you say you are looking for, I don't think it is a good fit. The CD player is also very good, but again, it is a bit laid back.
The Rotel is a very good unit, but it lacks dynamics. Biggest problem is the lack of real power (I think it is 40 wpc, and no real dynamic headroom). Stereophile did a comparison of this amp against the NAD C320bee not very long ago. I recommend you check it out. The "bee" bettered the Rotel in almost every area, so I would think that the bigger C352 would be even better. Now, I have a little problem with this particular Rotel CD player--I think it has a "hard" sound--the kind of sound audio gear reviewer's sometimes call "solid state sound." It just doesn't have that warmth or liquidity that natural sound has. More expensive Rotels are very good, but this unit is a little "steely" sounding to me.
Having eliminated those three, that leaves the NAD and the Arcam. Now, I have recently heard both and I think you would hear improvement with either one. The Arcam is leaner, so it will not give you the deeper bass, but it has a very articulate and clean top end that is very enjoyable. It is also a little more "up-front" sounding than your Yamaha, but in no way is it an "in your face" type of amp. It is just very good. Something you could listen to all day. The NAD is also very detailed, but it has a warmer sound, largely due to the incrediblely tight and full bass that it puts out. I find that it also has a sound that is very enjoyable, just a little different from the Arcam. I really think it really boils down to whether the Arcam puts out the bass that you want. If it does, it would be a great choice. If not, the NAD is the hands down winner in amps.
Now, between the two CD players, I think the NAD and the Arcam are about on par with one another. Both are among the few that have separate power regualtors for the digital and analog portions of the CD player (something that I think is a necessity for a good CD player) and both have done a great job in making the analog outputs present a wonderful, enjoyable sound. Again, it is a question of tuning as the Arcam is a bit more laid back sounding than the NAD, and the NAD more "up-front" with a richer sound. Both present a wonderful soundstage and have a very natural sound. I would love to have either one.
I cannot comment on the tuners as I have not shopped them, but I don't think the tuners are going to be substantially different in terms of quality or performance and is not likely to be a decision maker in deciding between two systems.
In sum, the Arcam is a nice flavorful Chardonney, smooth and breezy, and very enjoyable. The NAD, on the other hand, is a Cabernet Savignion, full bodied and a cornucopia of flavors. It is really what you prefer--one is not better than the other, just different. Either one will be a nice improvement over your current electronics, however.
Was it the PM7200 that you heard? I have looked at the american Marantz website and see no mention of the PM7200 only the PM7000, although they look very similar. Your comments seem to reflect the reviews the PM7000 has received so am wondering if was in fact that model?.
Marantz seem to have a habit of making hit or miss stereo amplifiers.
You may be right, although I thought it was the 7200 at the time I auditioned it. Regardless, it is the only Marantz integrated amp that is available here in the States. After reading your post, I did a quick check of the reviews offered by eCoustics and found this quote in a review of the Marantz PM7000 offered by TNT Audio:
"The problem with awards, and the more meaningful the awards, the larger the problem, is that they invariably raise the expectation floor. So it was with PM7000; it has been awarded probably the most significant prize on the Old Continent, and this has led all, myself most probably included at least to some degree, to expect much of it. And while it has no obvious vices (Marantz people are far too experienced for that), it doesn't offer any significant benefits either."
"Instead, it is a decent, economy class integrated amplifier, with very creditable power ratings into both 8 and 4 Ohms, well constructed, but musically unexciting. It plays fair notes, but no more than that, and you may find you like what the competition offers better than the award winning champ of the year. Must have been a lean year."
This review confirms my observations and I think that sums it up very well! It certainly isn't going to represent an improvement for David's system.