What is the Altec 604 sound?

In So Cal? You are welcome to hear my one-off, tri-amped, Super Big Reds using vintage Marantz equipment.  The cabinets are 15.5 cu ft exterior volume.

https://youtu.be/4MWmYYV1bg4

Beautiful system Toddalin, I would come to hear it gladly, but I am in Italy....

Pdreher thanks, The idea would be a 604 or 605 in a cabinet a little less wide than the 620 which is 26'. 
I will look into HiFi Haven.
About the sound, from what you tell me I understand that Altec are perhaps more delicate and less strident than Klipsch (Heritage, Forte, Cornwall)?
At low volume 60db are they still alive? My Avalon Indra (which have 87db sensitivity) at 70/80db are wonderful, but at 60db they fall flat. 

I have limited exposure to Klipsch speakers, but from what I have read on forums, Klipsch Cornwall can be fatiguing.  I did have a brief listen to Forte IV's and I thought they were ok, but prefer my Altec's,   I typically listed at 65 db average and they sound very much alive and dynamic.

I have Altec 604E from 2005.

I never listened to Altec GPA. I don’t know how do they sound. It can be different from old 604s.

My 604 is very easy to drive and sound is very dynamic without feeling of any compression. The bass is fast and has texture but not deep. In my 9 cubic feet cabinet it doesn’t go deeper than 40hz. High frequencies go up to 10khz, so I use supertweeters.But new GPA should be more extended on high frequencies.

These speakers wonderful for jazz and vocals. They can play rock and classical music too.

They can play in midsize rooms. Even 200 square feet is ok. Because the are coaxial they can play from 8 feet distance.

Here are my Altec 604E videos:

https://youtu.be/Nlo9qR4-I0c

https://youtu.be/ooFTaeJsdQ8

Model E was in production from 1964 to 1973.