I don't know all the specifics, but the new models have a 25 Watt triode/45Watt tetrode switch. You would have to have them side by side to compare sound. I have the old red amps, and they are VERY good. You get 25Watts triode only. I had them re-tubed with used old Mullards by Andy and Vintage Tube Services after a couple years. It was spendy at $800, but that took them to a whole new level. The amps had the original VTL tubes still in them. I am running Gallo Reference II Speakers at 89db sensitivity. The amps run them surprisingly well. I don't think you will be disappointed with either choice. Re-sale is holding for all of them too.