New to 2.2 Stereo...Pointers?


I recently read on this forum about the benefits of dual subs (and 4 subs). So I piggybacked my HSU sub to the SVS sub (which I use for HT) just to hear if there was any difference. There was. Bass sounds were level and tight where as before with the one sub sometimes some notes were louder than others. Also the depth and layering of the sound stage seemed to increase.

I own the Primare A32 power amp and Primare Pre32 preamp. The power amp has four sets of speaker binding posts. https://img.aussieaudiomart.com/uploads/large/914173-5b112ba2-primare-a32-aplifier.jpg
My speakers are bi-wired (Monitor Audio Gold 300).
The pre amp has 2 sets of analog (RCA) pre outputs.
http://a.scdn.gr/images/sku_images/013883/13883760/PrimarePre32backRGB.jpg

My subwoofer is a HSU Research VTF-3 MK4 and has two pair of high level binding post inputs and one pair of RCA low level inputs.
http://www.hsuresearch.com/products/vtf-2mk5.html
I just ordered a second HSU subwoofer, the VTF-2 MK2, with two pair of high level binding post inputs, two pair of out put to speaker binding posts and one pair of RCA low level inputs.https://img.canuckaudiomart.com/uploads/large/686729-267477a8-hsu_subwoofer_vtf2_vk2.jpg
I had the lone sub connected via the high level inputs to my power amps upper speaker posts and the sound was good most of the time. I don’t have room for 4 subs so that’s not an option.
Just wondering (when the 2nd sub arrives) if I should simply connect each subs low level RCA inputs to the preamps pre analog outputs OR connect the power amps speaker posts to the VTF-2 MK2 subs high level input binding posts then connect the output posts to the VTF-3 MK4's high level inputs? What has been your experience with multiple sub connections and bass integration?
mewsickbuff
I use the low level, UNLESS I use something like a stand mount speaker for mains. Then using the high pass, and speaker high level input. I keep the subs pretty close to the mains, normally inboard, and forward of the mains. 

Remember, above 80 hz or so, things can get directional.  Running  them inboard, can help with the MB a LOT, may loose a little imaging.

80 and below run them outboard, but  still forward of the mains, better imaging (no bass bins between you and the mains), but the timing might be off a bit. Add a .5 delay to the mains if you have that option or move (the bass bins) closer to your seated position. MORE bass, add a beard to the stand

Floorstanding mains, The bass bins are normally outboard, of the mains,
unless you're using a single bass bin.  I use it center forward of the mains..

This works pretty good for me.. 
Sorry oldhvymec, but what is a bass bin? I had the subs crossover set to the lowest Hz on their dials (30 Hz HSU, 50 Hz SVS). My speakers are full range floor standers.                                                
https://www.monitoraudio.com/en/support/past-products/gold-4g/gold-300/
Makes no difference how you hook them up. High level, RCA, no difference.  What you heard:
Bass sounds were level and tight where as before with the one sub sometimes some notes were louder than others. Also the depth and layering of the sound stage seemed to increase. 
Is normal and expected when adding subs. What you are doing is building a distributed bass array. Do a search. Four is usually optimal although I run five and found that to be better than four. https://systems.audiogon.com/systems/8367
What has been your experience with multiple sub connections and bass integration? 
My experience is the more subs the easier and better the integration. With just one its like you said, the bass is lumpy. With more its more level and clear and with four its downright holographic what it does to the sound stage. 

Also with one its a lot of work to find the best location with the smoothest response. With four they can go almost anywhere and it will still be very smooth and even and articulate.
Bass Bin, 250 hz and below. What you call a sub. Which is actually 60 and below.

The HP option cuts the mains, at around 60-80 you have to look it up, and make sure your SUBs (bass bins) have that option.  It helps with a smoother transition, There is usually a pretty good bump at 50,
(8 ft ceiling) and 70-80 with a 9-10 ft ceiling. That is why the room booms and you get the one note bass. 

Hay do it, however you like. I'm just telling you a WAY, not the way. BUT it works very well if you have a sub that supports a HP option, with speaker level input. Good option for HT setups and Main speakers without enough umph on the bottom.

It's usually a room treatment and placement issue, because mains doing sub, bass, MB, mids and high, make for a tough bill to fill with one single flat baffle on the left and right of you.  Timing is all over the place, do you see why?  Think like a mechanic for a minute. :-) XTreem, Near Field not so much. But a standard speaker placement. They arrive at the seated position at different times. You can make bass everywhere, and you will have BASS EVERYWHERE. You're not everywhere. See my point..

Different way of doing thing.

Regards