Subwoofer Basics Help

The issue I'm looking at resolving in my system is my speakers don't fully open up on the bottom end at low volume. My system has to be "loud" in my wife's opinion to fully open up. I'm ok with this listening level most of the time but would like same at lower volumes. I'm also curious what is missing in the bottom end of my Naim NBLs. Gotta figure out how to demo something, would buying a cheaper used subwoofer give me taste of the improvements? I don't have a dealers close to me.

Yes the record out is full volume. As others mentioned your best bet is sub with high level connections like the REL. 
 

You could use the volume control route out of the record out but you would be doing a lot of fiddling with it every time you changed the volume.

2 subwoofers seems to be popular. At what price point does a single subwoofer out perform using 2 subwoofers?

Two subs is popular for a very good reason.  Tough to answer your question in general because there are many differences within each brand’s lineup, but just to use one example I’d take two SVS SB1000 Pros at $950 over one SB3000 at $1100 especially if it’s primarily for music.  The SB1000 doesn’t go as deep as the 3000, but it still gets down to a legit 20Hz (-3dB) and you get the benefits of the subs not working as hard, providing a more even bass response, and dealing better with room modes/issues.  Just one example FWIW.

2 subwoofers seems to be popular. At what price point does a single subwoofer out perform using 2 subwoofers? Are there issues with subwoofers feeding AC noise into systems or grounding issues that impact the rest of the equipment? 

My vote is for REL also.  Buy a pair if you can.  You will get a more uniform bass response.  Hook you amp up to the high level inputs.  

Iso-Max makes a unit (Model SP-2SX) that will take the speaker level out from the amp or speakers and convert it to a line input. Thus, being able to use any powered sub.

ozzy

Give REL a call and they will walk you through specific setup based on your equipment. 

I’ve 300B SET mono blocks and run Rythmik and Rel sub pairs. Both brands are nice, but the small RELs have modest SPL with limited flexibility. REL is speaker level input; Rythmik is both. As I understand your connections, a high quality line splinter of turntable out can allow ready connection to sub and to power amp.

I have the REGA Aethos and had the same issue.  Ended up using this volume control.  

https://www.ebay.com/itm/264143836049 

Connect from RECORED OUT to this then out to subwoofer.  Works very well to control the sound level of the sub.   Each recording has different bass content so using this small control makes it very easy to adjust bass.  Placed the control on top of my shelf within easy reach.

I own a small REL. It's ok  However, I think they are overpriced for what you get.  Also, they seem to be the only major vendor pushing the high-level connection.

If you have variable outputs , call SVS subwoofers they can walk you through it

and from $600 on up they have a nice app to control your settings from your seating area which is very handy. And comes with Free shipping and a 45 day

trial and 5 year transferrable warranty. If later youdecidetogeta2 nd sub you can 

monies off.

Just get a couple of used RELs for cheap...that's what I've done and they work perfectly.

If your sub isn't powered, you can bi-amp (buy amp) to power the subs separately from the mains.  

I am driving my REL with the second pair of speaker jacks on my Cyrus integrated amp.   I used this sub in another system via RCA with OK results but honestly after hooking it up via speakon connector I think it sounds better.   I couldn't use it speaker level in the system it was in , but I really think these subs integrate well with speaker level input.   My second system has never sounded better.  

I think the only amps you can not do this with are true balanced differential output amps 

As a few users already suggested, you can connect from either the speakers / amplifiers using high level input to a subwoofer, no issues.  I have a pair of REL connecting this way.

Your situation is why there’s a variety of -3dB subwoofers that offer High / Speaker level inputs with varying levels of EQ adjustments which aid in a variety of speaker and room pairings. With proper positioning they can offer more detailed integration with lower frequency heft when the media calls for it.

The above suggestions are for -6dB sub-bass speakers. This lesser amount of low frequency output may not excite the rooms standing wave bass modes the way a poorly positioned subwoofer can increasing placement options. Being equipped with only the basic switched phase, detent crossover and volume, this manufacturer uses a speaker and or room formula to match their products to speakers and rooms.

References to "speed" and "musicality" are generally subjective. I’ve had both and subjectively, I undoubtedly prefer subwoofers over -6dB sub-bass speakers.

+1 for Rel. They are able to integrate easier than most other subs with their high level connection explained by bigtwin.

As for cost, that's gonna depend on a few things, mostly room size. The Rel's disappear when set up properly until the music calls for them, they add but they don't take anything away.

@musichead  Have a look at the line up from REL.  These powered powered subs simply connect to your speaker lugs on your amp or on the speaker terminals.  They do not compromise your system in any way.  The signal is amplified by the subs.  The only thing to watch for is the hook up on the amp.  Wiring is different depending on amp set up.  Stereo or mono block.  Balanced or not.  The manual shows every scenario. 

https://rel.net/product-category/powered-subwoofers/ 

Is the sub powered or unpowered?

If powered, the “pre” out works.

You can't use a record out unless it is after the volume control.

If you are  using a powered sub, the input impedance is often 100x higher than your speakers and won't be a compromise at all.  With a passive sub it will.