Harbeth Compact 7ES ll in a large room

I'm moving and my listening room will be 20.5 ft by 15 ft.
Will my Harbeth Compact 7ES-2 with a Rel Strata lll driven by a Sonic Frontier Power 2 amp be sufficient.
I ran a pair of Compact 7ES2's with a Rel Stadium II or III? (also ran the Strata III on loan before buying the Stadium) in a room that was 15 wide by 23 long and opened into a hallway and a dining room on one side. I first ran the Harbeth's without the sub as I had moved my system from a small room upstairs to the larger space described above. It sounded very good and I was able to move the Harbeth's away from the short wall and room boundaries where this was not possible upstairs. I did, however, feel the desire (need?) to try a sub to see if I could better pressurize the room and increase the scale of the sound. I tried the Strata III on loan from the dealer and it did most of what I was looking for but decided on the Stadium to hedge given the size of the acoustic space. This combination worked very well as far as it went and I think you will obtain plenty of bass, scale and dynamics if you choose to go that route. Ultimately, after about a year or so, I sold the Rel and decided to look for a full range speaker that would do what the Harbeth's did very well but with greater scale, dynamics and an ability to really project sound into the room without the need for a sub, which I feel inevitably degrades coherence. Short answer to your question--Yes, it will be sufficient. Longer answer above.
Yes, very much so. no worries.