My, my… that’s a big one! My one is only 439mm… Now I feel totally inadequate? However its height is 138mm, so is there any truth about thickness being better?
Normally the 8 Ohms figure is accompanied by what Watts it can drive into this. If this doubles into 4 Ohms, then your amp has good current.
My amp only mentions DBs in association with "signal to noise ratio" and "frequency response," but as to what's a good reading, that's anybody's guess......sorry.