Sub/ triangle

+1 Mr. Reynolds. There seems to have been a great deal of subwoofer talk centering around the term 'speed.' Personally, I have yet to see a measurement or experienced even very modest subwoofers that reacted slowly to a given input signal.

Out of phase recordings are notorious for putting the subs driver out of sync with the recording. IMO having the ability to invert phase via remote control at the listening position is a must.

There are many other aspects of subwoofer design, performance, and control, that could easily fill the taste and requirements of individuals as well as making their integration more seemless.

I have Triangle Titus also. Wonderful speakers that do what they do very well, but low bass extension is not what they do, so generally a very good candidate to supplement via sub(s).

If you do not care about or need bass extension below 50hz or so to be happy, I'd go sans sub with the Titus and get them to shine as is.

If more full range sound is the goal, I'd focus first what is needed to get sub integrated a best as possible for best sound without "muddying the waters".

From there, I would think about using two matching subs in order to help normalize bass response throughout the room further is bass is good in one listening position but not so much in others. Next step beyond that for same reasons would be to add additional subs, but benefits become increasingly marginal from there.

Probably go with Sunfire JR. sub...or small HSU...something known for speed and clarity...which is the signature French sound