How to optimize sub integration with 2 channel?

Since OP's PrimaLuna Dialogue HP tubed integrated does not has pre-out/power amp-in, high pass filter will be limited to speaker level connection. 

If you do not wish to use a high pass / EQ for the main speaekrs there IS a cheat you can use. :) Stuff the ports, converting them into sealed speakers. This will give them a higher cut-off than normal and increase power handling.

This will also make subwoofer integration a little easier. Of course, many audiophiles swear sealed speakers are better sounding no matter what.

Having said all of that, you really should wait for your speakers to arrive, and figure out your placement, etc. I love my sub but I end up using it only for movies.

Best,

E

@willemj . thanks for info on hi pass filters and XOs. 
that is my weak point. need to do some research. 
Im interested in the Zu Audio Undertone Sub:

I am interested in this sub: the Zu Audio Undertone subwoofer http://www.zuaudio.com/subs/undertone.
It does say there is a Signal Processing Bypass, but I dont know how it works.

here is a pic of the backside, and connections options: 
From Zu's website:

 "Line-Level Input: yes, RCA (left and right summing)
Sub Line-Level Input: yes, RCA
Speaker-Level Input: yes, 5-way binding posts (L/R summing)
Tunability: yes, very
Signal Processing Bypass: yes, switched for those that want to integrate more elaborate signal processing but desire to take advantage of the excellent amplification of Undertone."

Also: from Zu website, "It is a down-firing subwoofer with active signal processing and built in amplification. It accepts line-level feeds (RCA left and right summing), sub feed (RCA) and speaker-level (five-way binding posts, left and right transformer isolated and summing)."

Here is the best image I could find for the back of the sub, and its connections/options: 
https://static1.squarespace.com/static/51dd8a95e4b0ff2f7c9874ae/59e64781f43b55b96d873030/56d0d5d286d...

@imhififan 
Thx. But let me try and clarify.
The PrimaLuna has a mono out that is used for the sub. I'm not sure if it is the best solution, but I Currently use a single RCA cable to run from the Mono out of the PrimaLuna to the LFE in my current sub (a 10 year old Martin Logan Grotto, 10", 200-250 watts or so). 

Also, the PrimaLuna does have an HT Bypass that only uses the Amp section of the PrimaLuna. Is that what you mean? 
thx

@erik_squires .
thx Eric. I have tried stuffing the ports of my Dali Helicons before.
And tried a variety: 1/4 stuffed, 1/2 stuffed, fully stuffed.
I found that beyond 1/4 stuffed (or so), there seemed to be too much loss of mid frequencies. 
but I'm willing to try again when I get a new sub.