[closdesducs]

...so take my experiences, thoughts and observations FWIW.

I've owned a stock pair of Altec 846A Valencia's since 2012 that sounds sublime with my Shindo tube system, but also does very well with my backup gear which consists of older Audio Research tubed amps/pre-amps and a McCormick DNA-1 SS amp.

About a year after I acquired the Valencia's, a pair of Altec 604-8G's were available locally on eBay here in the Southern California area. I contacted the seller and he agreed to demo the speakers for me. When I arrived at his office, he explained that the 604's were original monitors from a recording studio that was no longer in business and had been dismantled. For the demo, the speakers were hooked up to a vintage Crown SS amp and a CD player. He played some CDs of my favorite music (jazz, women's vocals, classical, Hawaiian slack key) that I had brought with me.

I enjoyed the listening session but my take on the 604's (bearing in mind that a SS amp was driving them with a CD source of unknown quality), was that they very "truthful" speakers revealing both the good and bad, "warts" and all of the CD that was being played; whereas my Valencia's were more "musical", lush, and forgiving (i.e. good recordings were elevated and so so and mediocre recordings were easier to listen to).

The Valencia's filled and continue to fill my listening room and while the 604's achieved equally loud volumes, their sound was very directional, very focused. Qualities I imagine that would be greatly valued by a recording engineer.

Despite their sonic differences, I was still impressed by the 604's. Unfortunately the seller politely declined to accept my offer and pull the speakers off of eBay. I kept an eye on the 604's, but the final winning bid well exceeded my budget at that time.

With regards to the O/96's, I've heard them paired with Shindo gear on several occasions and have enjoyed their sound immensely as well. I would say their sound is more towards the Valencia side than the 604 side in terms of the Altec speaker spectrum.

Best wishes on your quest.