A question of bass... Several actually.

Keep in mind Buff is a Dynaudio dealer.

Man, Bill, you ARE the Dealer Police, dude! I'm not a dealer, but I play one on TV. Depends on what they actually said, but in some sense your dealer is feeding you a bit of crap flap jacks with some crunchy bits and no syrup to cut that crappy taste. I like Buff's dating analogy. Try different things and see what works for you..there's no better way to figure it out and have fun along the way (hopefully).

My opinion is that subs are tricky to integrate but it can be done to rewarding effect with a decent sub. Speed in a sub is certainly important, but keep in mind that a sub is really to augment the low end, not to fill it in where it's missing. The sub usually produces sound that you feel more than you hear, though you can certainly set them to take over in the range that you hear, it has not been my experience that they can substitute for a speaker producing good,tight, natural-sounding bass below 35hz. A good sub in the affordable realms are those made by ACI (IMO). A great sub if you have more to throw at it is JL Audio Fathom. Bill's already making sure I'm not selling either one :-P Again, I don't believe either one is going to substitute for a speaker producing good detailed tight bass down deep and low, but they certainly can be integrated with some effort to rewarding effect. I think many folks end up setting them up with way too much volume and get tired of the one-note boom boom intrusion on their music. In that sense they'd be a poor choice (if you are not willing to put in the time and effort to integrate them well don't bother). I've only heard Dynaudio speakers, though not the ones you are talking about, at shows and have never heard the Regas. I'd have to agree with your dealer on one point: in my experience you do indeed have to pay significantly more to get speakers that reproduce excellent bass in the sub 35hz regions. A larger volume cabinet alone, or larger drivers, or more of them, do not assure you of anything at all (think white van speakers as the extreme). To get a firm grasp and render natural timbre and detail in those lows definitely is not the forte of inexpensive speakers...at least I haven't heard any that do it very well (read: Lifelike). That's not to say there are not speakers in your price range that can produced a rewarding sense of a low end...it's just not likely going to drop into the natural realm of those notes in reality. You can certainly throw your money at a $1000 speaker that reproduces sound below 35hz, but I truly doubt it will sound very good. Better to put it towards a great monitor...at least in my experience...which can be far more musical, engaging and rewarding at that pricepoint (this is a broad generalization based upon personal experience with the retail price of new speakers - take it for what it cost you). If I wanted to spend that kind of money and actually get some decent bass, personally, I'd be looking at vintage Klipsch Cornwalls paired off with a decent tube amp of about 35-70 watts, but again, that's a personal choice and YMMV. As far as why it does cost more to get good bass from a speaker, I could not do justice to that explanation. There are several very fine speaker designers who participate in these forums - Duke at Audiokinesis, for one, does a brilliant job at seamlessly integrating a very significant low end with at least two of his designs I've heard. Daedalus also excels in this realm...not sure if Lou is participating in these forums. Either would address this issue with far greater authority than I ever could, and perhaps spank me for saying something inaccurate...but that's my experience/opinion for what its worth.

I'll step out on a limb even further and give you my theory why it cost money to make bass go low and sound natural. Now daddy may be taking his belt off! Obviously there is the money in the actual driver, driver materials, as well as the crossover (materials). More so, perhaps, I would guess that a very dense and rigid housing is paramount for bass drivers. If you think about a large driver bolted to the outside of a wood cabinet producing significant energy within an enclosed wooden box, you start to realize that the more that mounting point and or cabinet walls flexes and resonates, the more of the energy is wasted in that movement, and the more potential for distortion of that energy (read: loose, inaccurate bass). I'd hazard to guess that is where the lighweight floorstanders tend to loose the race in the low end. Though they may produce sound down there, it may not be accurate or lifelike. I can say from my own recommendation of vintage Cornwalls, that you could do much to improve those speakers by adding additional bracing to the inside of the large plywood cabinet, as well as in adding some better sealant (caulking) around the seams of the back and drivers. There are several other tweaks you can do there, but I digress. The best low-end performers I have heard have evident attention paid to a rigid, heavy enclosure. I've not heard any that can perform as well which choose very lightweight materials as an option. The possible exception that comes to mind is a speaker I heard recently that uses an open baffle woofer (no cabinet at all), the Gradient Helsinki, which certainly surprised me. Oh man, I'm afraid I'm not going to be able to sit tomorrow.

You can only get so much bass from a 6.5" driver. After a point design makes the bass peaky and boomy on smaller drivers. Initially it gives the impression of more bass but as Jax2 pointed out it becomes one note boom. Move to a floor stander with a larger woofer for deeper bass ($$$)or a sealed box sub for responsive low bass. I would also recommend good solid state amps to dredge max bass from speakers though I prefer the sweet midrange of tubes.
A sub & monitor speaker combo will allow solid state bass with tube midrange and the stellar imaging of a monitor speaker.

I integrate an ACI Titan II with ACI Jaguar 2000's for a very nice full range. The signal to the Jaguar's cuts off at 85hZ thanks to in line filters and the Titan is quick and tuneful. Admittedly intergration can take some time fiddling but once it is there you are good as long as you don't make big changes in room arrangement or gear. - MHO

Rhanechak - what amp did you have driving the Dynaudios? My experience is that the A 72's can go very low and loud when driven with sufficient power (300W or more into 4 ohms). The Regas on the other hand are more efficient and can run on less juice - like that produced by a Rega amp...

Bass reproduction is a two-way equation, power to control vigorous driver movement and a combination of driver diameter and throw to move a lot of air. The smaller the driver, the faster and further it has to move to displace the same amount of air as the larger diameter driver. I have heard phenomenal bass from stand mount monitors when driven with lots of clean power. They weren't hitting impossibly low notes, but the notes they were hitting were controlled, clear and loud.

So, I might say that while it is not "necessary to spend $1000 per speaker or over to have audible, palpable, appropriate bass reproduction" it may be necessary to spend $1000 per channel of amplification to get it.

Subwoofers are an entirely different story, and the trick there is that most better ones come with their own capable bass amplifier designed to control the woofer. The idea provided above to split the signal after the preamp and drive a high quality monitor with a high quality but lower wattage tube or SS amp, letting the sub fend for itself is a good one. Sub speaker integration is usually possible, but takes some fiddling, and may actually require trying several subs with your system to find the best match.

With either the Rega or the Dynaudios, you should not need a sub unless you need the walls of your house and your heart to move with the music. As long as you feed either pair with adequate power (which would be more in the case of the 72's), they should reward you with nearly full range sound.

Good luck.