Compatibility between speakers and sub.

My recommendation are the Vandersteen subs. They use an external crossover between the amp and preamp. When the crossover is dialed in, you are basically plug and play.(Unless you get the new Sub 3's which have a graphic equalizer that needs to be set up).

You can buy a number of subs for less, but integration will be more intensive. I have owned the 2w, 2wq, and Sub 3, all performed seamlessly with my speakers.

Bob

I’m not sure I understand. If I have an integrated amp, does that make a difference? Are you talking about the amp and preamp within the sub? Feel free to speak to me as though I am a third grader.

After spending a pile of cash trying various subs, the SVS SB2000 Pro was finally able to fit in with my room and Klipsch Lascalas. I thought I had given up on a sub ever being able to blend in. They have an app that you can use to tailor the frequency appropriately. I'm so glad I didn't quit searching. Punchy, clean, musical, deep and rockin'. Just sayin' Try them out. five stars

Get a high pass crossover and use what ever sun you want. Matching is mostly about the crossover. I mean most speakers have totally different tweeters, mids and woofers…. The crossovers make them play nice. 

Does your integrated amplifier have R/L RCA sockets labeled Out or Output?

ATC offers the C1 which can be connected to their active speakers. ATC's Pro 12 Also connects to their speakers. They suggests using Dolby DARDT for best performance.

I bought SVS SB 3000 subs and I’m quite happy. I use the preamp out of my musical fidelity amp. Thanks everyone for your help.

REL are about as simple as it gets. Use the high level input (which draws the voltage directly from your amps output stage) and dial in cross over point and gain

Congratulations.

The SVS positioning suggestions appear generic. Their Sound Path Remote would make trial room positioning a breeze. This is a link explaining the subwoofer crawl. You don’t actually need to crawl unless you want to check it out for yourself.

https://www.youtube.com/watch?v=AV3oLLMgS-M

You should be able to find a low frequency test cadence on a test CD or a download. Draw a map of your room. While the cadence is playing through the speakers and sub note the loudest bass mode areas.

Decide on a convenient subwoofer location in or near a mode. Begin adjusting the frequency and Q to more closely match the presentation of your speakers lowest output using the cadence then actual music to your liking. These settings should be saved to memory in one of the application presets.

This may seem daunting at first, its not. There’s no rush, take your time and enjoy the flexibility of your subwoofers processing.

OP here. Thank you for all your help. One thing that still confuses me is that my speakers list their low frequency roll off when it is -6 dB instead of the -3 that other people use. That is 48 Hz. Should I guess what the -3 rolloff would be or use the -6 or something else?. When I change the low pass filter, I don’t notice a change in the sound, although I’m sure it is there and this is about my ears. So if someone else’s ears are more sensitive, maybe they would know whether this six verses three thing is significant. Both the speakers and the subs are sealed boxes with gradual roll offs, by the way.

The SVS application may show you the lower frequency of your speakers.

Maybe someone at the AVS site can help you with your setting up. In the end when you gain some proficiency your setup will reflect your taste.

The SVS guideline is 10 Hz above whatever the -3 roll off is. They weren’t able to be helpful around addressing the minus six question. Also, this seems as though it’s a bit of an arbitrary call since I’ve seen conflicting information from sources just as reliable, albeit not the brand manufacturing my subs in particular. On their site where they have speaker matching, they suggest that I use 63 Hz, but they have that same number for every single Atc Speaker despite the range of different frequencies, and the 10 Hz above the 48 that SVS told me to do would be 58. Perhaps the difference between 58 and 63, or 70 if I take my guess about where the -3 roll off is not significant. I don’t know. That’s why I’m trying to find out more about this. It makes me insecure that I’m just picking a number out of thin air to some degree here.

get an app and some full spectrum pink noise to measure the f3 at your listening spot,  i bet it will be lower than you think.  

after many years of subs i felt they sounded great most of the time but caused some issues and were only useful with a handful of recordings.  

i am happier with the sound of near full range speakers and a robust amplifier.