MD, welcome. If you mean in addition to the M60s, my view is that the QS surrounds should come next. The bass from the M60s is good enough so that getting a sub, while desirable, can be delayed. Since the M60s can provide a good "phantom" center for someone sitting about midway between them, a separate center speaker can also be delayed. A very wide-dispersion set of side surrounds(such as the QSs)helps greatly for movies and also for music if DPLII, etc. is used to extract the ambience present in two-channel music material and steer it to the surrounds where it belongs. Although the 2600s could also be temporarily used for that purpose, the QSs would be better and the 2600s could be tried as back-surround speakers instead.
