I noted when testing the 416's that the Z-max went to 204/187 ohms. I used to have a pair of 416A's that were in the 200+ ohm range also. Read that as might not work well with some SET amps(?). With my Norh SE-9, I found a little too much warmth in the midrange. I used a stock Altec N501 crossover with 511B horn. I originally tried a Pi crossover(2nd order low-pass/3rd order Hi-pass) and could not get phase right. The stock Altec N501 is 2nd order hi/lo pass w/L-pad. Well, the stock crossover is okay, but HF compensation might improve it some. When I connected up my McIntosh MC240(40w/chnl using 6L6GC PP), I found the sound much tighter, the bass from the 416's is decent, goes lower than my 2226's, but I find myself prefering the voicing of the 2226's over the 416's. Overall, the sound is decent, but I will return to my beloved 2226's and the benefit of being able to have smaller cabinets. The 2226's don't need the refrigerator sized cabinets that the Altecs need. For anyone with a 6BQ5 PP amp, the Altec system might be your best bet, for my SE-9, the JBL 2226 is my best bet, the MC-240 can run with just about anything.
By the way, the Model-19 from Altec was made to crossover at 1500hz, I happened to be able to peek at a schematic briefly and it resembles a Pi crossover with just a little bit different attenuation/HF compensation network. Funny when you think about it, Altec pushed 500hz/800hz crossovers for some time until the Model 19 came out, and it is regarded as one of Altecs best for home HI-FI use. By the way, Great Plains has brand new 416C's and 902's for sale for anyone looking to build these infamous 2-ways from the great vintage past. I am not associated with Great Plains, just always see hobbyists looking for sources for projects.

Thanks for listening, as soon as I get the Altecs out of the living room, time to bring back my 2226J and put my new 902's on my wood horns and put my old "standard" system back together again. JBL/Altec are both very good choices, the difference to me is in the midrange "voicing", and for that, my preference is the JBL!!!

Cheers, Ron