Best musical sub around $1k


Looking for some advices on sub.

I am deciding between Sonus Faber Cremona Auditor + sub or go full range and get Cremona. If I were to go with Auditor + sub, I will need to keep the cost down for my decision to make sense, hence the $1k budget. I like the stregth of mini-monitor - imaging, better coherence (2-way vs. 3-way), and easier placement. But Auditor needs to play loud to sound full range and I don't have that option most of the time due to my power amp (BAT VK-75SE) and small kids. So getting the Auditor will require a sub for my need.

So what sub will you recommend? I had a REL Stadium III before, but price is out of my range right now. Cremona sub is also too expensive. Are the smaller REL as good as Stadium III or I am better off getting an older Stadium (II ?)

Or to complicate the issue further, get a floor standing Cremona instead?
semi
Mt10425, so the sub you are referring is a DIY or something I can buy? Other than REL, what else is comparable? Thanks in advance.
Mine is an Art of sound "Tycus". I've matched with Tannoy Mx series speakers.
Running a PSB Subsonic 7 here. 330 watt on-board amp, 15" sub. I have it crossed over at around 45hz which picks up where the PSB Silver i's start to really die off.

To be honest, it's really a lot more than I need. Musically, it does quite well down to a reported 25 hz and reproduces heavy bass notes with ease at my listening levels.

Then at $600 (open box return, list at $1k) I think I got a steal.
Try listening to a Boston Accoustics PV1000. Small, powerful and musical... they sell for about $750.00 used and have a nice look to them.