Using 2.1 stereo and sub with Mac MX132 or MX134

Hi, I want to buy a McIntosh MX-132 or MX-134 new or used, but am puzzled about one thing: how to use the subwoofer while listening in stereo, a 2.1 setting. I want to connect my REL Stadium 3 to the Mac but I want to hear it by choice to while listening in Stereo. How can I make this possible. If not, what other pre-amp has this possibility (Krell, Lexicon, Classe)?
Kind regards and greetings from the Netherlands, GĂ©rard Hendriks.
The 132 will not allow this, and pretty sure the 134 will not either. Too bad, a frustration with McIntosh.
For those processors I have used that allow such, the Proceed PAV/PDSD and California Audio Labs both allow this option.

A nice to have.
I have a MX 132. You can use your sub crossed over(Only @ 80HZ.) This is the same, whether it is 2.1 or 5.1.
The sub is either On or Off for both HT and Stereo.

I use Vel HGS-10 with M/L Aeris I front speakers, Bryston 9BTHX.

The 134 allows you to specify 'large' or 'small' for any of the speakers you have. 'Large' means the speaker can handle frequencies lower than 80hz - or whatever you pick. When you use 'stereo' mode and have used 'setup' to inform the system you have a sub, the sub will be fed. If you want to toggle the sub on and off, do it through 'setup'.