Does room size affect volume and bass?

Oof. In acoustics (as well as a lot of other areas) there's this thing called the inverse square law. Basically, SPL decreases inversely proportional to the square of the distance from the source. So, go from 1M to 2M and the SPL drops -6dB. In open space. In a real room it's more complicated. The direct sound drops according to the inverse square, but the reverberant field does not. Also, low frequencies use the room surfaces and load up like horns: freespace = 1 , hemisphere = 2X (same acoustic power into half the space), quarter space (intersection of 2 walls) 4X; eighth space (2 walls and the floor) 8X. And it's all frequency dependent. This is why speaker placement matters so much. 

But SPL at the listener's ears is a combination of direct, reflected, and reverberant levels. Here, halving the room volume, all other things being held constant, the same energy input into the room will be doubled per cubic foot, and that's 3dB. 

So, yeah, the dealer is kinda correct, but in an oversimplified way. If your room is acoustically very absorbent it might take even more power. If you load your speakers closer to room boundaries, we already covered that. At best, the answer is a qualified maybe. In any event, listening a realistic levels in a good sized room is not something most HiFi speakers will do, they just can't move the air. You need some big Klipsch or real JBL monitors - S4700 or such. Full disclosure, I've never been a Klipsch fan, and JBL L-100s are simply terrible. But the new JBLs 3900, 4700, are simply spectacular.

I listened to the Sonus Faber Cremora at a dealer’s showroom. It sounded beautiful as long as the dealer played his choice of tunes. But, when I asked him to play some rock music (Green River -CCR) boy did they crack and pop, the dealer immediately lowered the volume.

So, I say if won’t play what you like at the dealers show room do not think it will behave differently in your home.

But more specific to your 3-year question, yes, the room size does affect the bass quality and amount.

ozzy

As Panzrwagn describes the situation, the dealer is correct that you will need less acoustic output of the speaker to achieve the same volume level in the smaller room.  The question that cannot be easily answered is:  will that be enough?  If you normally play music at very high volume levels, a small stand-mounted speaker  like the Electa Amatour will be stressed and will probably not sound their best.  If you like the sound of these speakers with the vast majority of music you listen to at the volume level you mostly listen at, you have to decide whether it is worth while giving up on some head-banging activity.  All choices involve some compromises in certain areas of performance.