Are Monitor/Subs More Room Flexible?

David -- yeah, that's exactly what I was thinking. I now have a very large room, and I antipicipate getting smaller also.

I would agree with your statement generally speaking with two comments:
- more flexible yes but not necessarily better sounding due to the need for quasi-perfect integration that is often under-estimated
- if you can bi-amp and modify the power delivered to the woofers vs. the power going to medium and tweeter (e.g. Linar 10 5.1ch integrated), you can have a very flexible solution without a sub (although you virtually mess with the "cross-over" and may affect the integration as well)

The challenge for a monitor/sub combo in a large room is for the monitors to be able to fill the room with realistic sound levels. I also agree with Beheme that monitor-sub integration is non-trivial. The advantage for the combo would be the opportunity to optimize soundstage imaging with proper monitor placement and to optimize room resonance control with proper sub placement.

Large speakers without subwoofer support often require large rooms. Listeners have to be able to get far enough away from the speakers that their drivers can integrate together to provide good imaging. Too close and the distances between drivers begin to impose their own dimensionality on the sound. Of course, the complementary benefit is that bigger speakers generally can go louder, so as to generate adequate volume in a big room.

Perhaps somewhere in between is the most flexible compromise. Maybe a monitor/sub combo with larger (the old "bookshelf" sized?) monitors -- loud enough for all but the largest rooms, but not too big and retaining placement flexibilty.

I think David hit the nail on the head; however this addresses the optimization of bass levels only. In my experience, Monitors are perhaps a little more difficult to position, and integrate with subs. Some are harder than others - eg, my GMA Europas were particularly hard to optimize. IMHO, the decision to use Monitor/Sub vs Full range is nearly as room dependent as is the decision on which full range to choose.

Interesting comments. I guess to be concrete ...

Right now I have an old pair of Lineaum LS-2 towers that I still quite like (really clean mid-range and treble to my ears, big soundstage, etc.; they just sound good!), but which have sort of weak and uninvolving bass.

The path that brought me to this question was:

I first had the idea of looking into the monitor and subwoofer approach, and listened to the Era Design 5s and Paradigm Studio 20s. But I actually didn't leave convinced they sounded better than my existing speakers.

So someone suggested I look into a subwoofer to augment the weak bass of the Lineaums and not worry about replacing them just yet.

But notwithstanding the large room, it seems to me there are some great deals in floorstanders (from Joseph Audio, Totem, etc.). But digging more, I've seen commentary on the room size issues with these speakers.

So the best options I see are:

1) buy a good subwoofer now, with the possibility of maybe upgrading the mains latter (probably following David's suggestion).

2) replace the Lineaum with another floorstander in the used $1000-1500 range.

Of course, 1 and 2 aren't completely exclusive (I could get a sub and do 2 also).

There's another option, which is to just spend my money on music!