Integrated Tube Amps with Subwoofer out?

Any pre with a pair of outputs will work, as will a Y splitter.

Here’s the trick. You need to make sure the sub and amp input impedance are high. So long as that’s the case, you are good. 
If you want to put in a high pass filter in the amp, you can build one with a single cap.

you should ideally use speaker outs (not pre out) to drive a sub (or better yet a pair of subs)... rel and other firms do this, many (myself included) feel this really helps the sub(s) work and integrate better for hi fidelity stereo sound

Agreed, many subs these days have a “high level” input that is directly connected to the speaker terminals to deliver the signal. As mentioned, REL is one such manufacturer. This method opens your door for many other integrated amps. 

If you do go with speaker level output from the amp to the subwoofer the Raven Audio tube amps have an interesting feature, a pair of speaker outputs with a selectable high-pass crossover at 80Hz or 100Hz that means those bass frequencies are removed from the amplifier section and passed off to the subwoofer, effectively make the amp 2 to 3 times more powerful, according to Raven. My Blackhawk was built before that feature was added so I can’t testify to its effectiveness. When I had an HSU subwoofer the high-level outputs were what were strongly recommended by Dr. Hsu.

+1 on all comments above. I have compared my sub from a pre-out on the preamp to the outs coming via the speaker terminals on the amp. It is far superior when it comes from the speaker terminals. Here's a helpful video (short): https://www.youtube.com/watch?v=bnQOjCuoR9k&ab_channel=RELAcoustics

Raven Audio tube amps 

Thanks for the tip on Raven, it looks like these are made about an hour from where I live and I love that!

DOH!!! I'm so sorry I misread this as an ask for a Tube PRE.

My bad.  The Luxman LX-380 will fit the bill, and let you put a cap in to use as a high pass filter.

This is a non-issue. There’s two simple solutions. Easiest is a LOC or Line Out Converter. Next easiest is to modify your integrated. The mod costs about $2 total for 4 resistors and can be seen in its entirety here.
https://systems.audiogon.com/systems/8367 Look at #26 of 47. That’s a close-up of the 2 resistors.

All you are doing is adding one 10k resistor to drop the voltage, and another about 1k to provide input impedance to your sub. The complete circuit diagram with explanation is here. https://www.epanorama.net/circuits/speaker_to_line.html

If you buy a LOC that’s all it is, two RCA connected to 4 resistors just like the circuit above. The LOC is cheap and easy but looks tacky. The mod is a little bit more difficult but looks factory original. Same result either way. So if you buy a LOC don’t waste your money, just get the cheap one from Parts Express for around $10.

The Raven is of course totally the way to go, and will be better in every way. Their sub out is even switchable. Check it out.

The Parasound HINT has a subwoofer out.


Sorry - didn't see the "tube" qualifier.

You can use this for $40- Russound ADP−1.2 Speaker Level. I used this to run dual subs out of Leben amp.

Itis not necessary to have a preamp out for a Subwoofer,crutchfield sells a adapter 
you just put a awg 16/wire in the + - for each side of adapter ,and either a 
banana or spade into speaker terminal it is actual more accurate 
and crutchfield , or call SVS subwoofers they can tell you exactly what it is called for under $30 I used one with my Krell integrated worked great. 

Primaluna integrated amps have one. All tube. 
Decware has a line out intended for subs as an option. They add tube rectification which is awesome too. 

Use any integrated you want. Simple elegant solution. Give Jensen a call and they will set you up with any type connection that fits your situation. Under $200 I believe, very friendly service. 
https://www.cs1.net/products/jensen_transformers/SC-2NR.htm

Primaluna has sub out

self powered sub?

where’s the crossover/filter?

IF you send everything except low bass to the amp, after sending lows to the self powered sub, then the amp no longer has to make low bass, and neither do your main speakers.

especially important using tube amps, reduces needed power, size, heat, offers optional placement perhaps.

and, choice of mains is widened

I tried unsuccessfully to integrate a sub using the line outputs of my integrated tube amp when I had it. Get 2 subs and go directly from amps to powered subs. Much easier and sounds much better, bigger soundstage, clearer, tighter bass and seamless integration. You do not need a sub out as others have said previously. 

Rogue Audio Cronus Magnum integrated amps have a variable output that can be used for subwoofers. That's what I use and it's fantastic!

Black Ice Audio (formerly Jolida) has a new line of integrated all-tube amps that all feature (mono) Sub outputs.

I’m using a Line Magnetic LM805ia (not equipped with sub out) with DEBRA sub array. I have a line out conversion recommended by James (company owner). This is the same/same millercarbon mentioned. I used high quality Vishay resistors. Problem solved. 

I use the outs on my Ayon Spirit III integrated for stereo subs.  Love it.