bergkamp,
could you try one thing with your REL, keep the cutoff at around 20-25 hz, keep the sub in a corner and then try to dial it in..the moment a sub dials in into a room, it is almost magical it couples not only with the speaker but also the room. most folks try out the rel with a high crossover and low gain and that is the wrong way to dial in a REL as the rel is a cross-overless design and its upper curve and the speakers lower curve are supposed to add up together to give an somewhat even response
Looks like you have really started to appreciate the effect of the REL! Glad to hear that.
I am sorry to interrupt but a few points mentioned in this thread do not go with my experiences.
First is the use of bookshelfs and subs. If one really wants to get the best of both highs and lows, a pair of floorstanders each with a "musical" sub will be the ultimate (I am not bringing in the cost factors). The mains positioned to get the best mid-range performance, far away from boundaries, and the subs augumenting the bass where the mains let off, nothing beats that set-up. Whatever the crossover design, let us not forget that it is not a brickwall where one driver stops precisely at "x" frequency and the other starts exactly there. There will be overlap, no doubt, and that is where the integration becomes so important.
There is no substitute for connecting the subs from the main amplifier outputs as a sub for music needs the same signature of the signal going to the mains. All it will do is to look at it and reproduce what is necessary when and the impedance of a sub is hundreds of times more than the 4 or 8 ohm of the mains and therefore, will hardly affect the current going to the mains. The sub's amplifier takes care of the rest.
I don't mind repeating it from my earlier posts, Rel, Bag End, Vandersteen and M&K produce some of the best subs for music but a lot of effort is needed to get them set right. A 10" driver is a must as minimum or multiple 8" drivers. However, larger ones like 15" bring in their own problems. I have used the Rels with 150W power for music with great satisfaction and do not think 500W is really needed.
If someone is promoting a HT sub as equally good for music, I usually take it as a joke.
These are not observations related to "high end" manufacturers but even those of "more affordable" speakers and subs like Polk Audio promote similar views on use of subs for music.
A very simple practical illustration. I am sure practically all of us in this forum enjoy Rafi's songs and perhaps one of the most immortal songs, Tere Mere Sapne from The Guide. In my earlier days, I had always wondered (even with good CDs playing the song) why there was always a mismatch when he comes from Tere-Mere to Sapne, some pitch issue as the 'Ne" used to become distorted. His voice is flawless, no doubt, so even such simple things stood out. Once I got the subs (pair) and tuned them properly with my mains after a lot of efforts with various test discs etc, suddenly the same song started sounding much smoother. There is no flaw in his pitch variation. Another example is his piano-song in the movie Barhmachari where each line in the three stanzas are sung in three different pitches and with a good system able to reproduce it, you will suddenly realise whether there ever was (is) another human with that sort of control over the pitch and the silkiness of sound.
Just some views from experience, right or wrong.
thanks and cheers.
murali