the R105/3 had an optional kube 200 that extended low bass but added a lot of distortion and doubling in the process the kube also tamed a slight rise in the upper mids that you could probably dsp out. The R107 and 107/2 required the kube but the r 104 and 105/3 didn't. I remember both having those stupid wallwart power supplies that some internet research could probably get you the specs for.
