So... The PM8004 has about 100 hours burn-in and it sounds quite different now. The lows have settled down and the mids and highs have opened up nicely. Unfortunately, the PM6004 only has about 30 hours on it, but it will have to do for our purposes.
First, for the comparison I am only using CDs. (I know... kinda lame, but hooking up the turntable on top of this stack is problematic.) I am running a Marantz CD5004 (which sounds a little bright) into the amps, then into Epos Epic 2s, which tend to be a little forward above 7k Hz, but these are not as bright as Epos typically are.
I ran the 1060 against the PM6004 and the PM8004. The 1060 is in great shape, but does need a recap, which will obviously affect the results quite a bit. I dialed the midrange back a notch and the bass forward a notch on the 1060 since those old capacitors can thin things out a bit. My buddy (who is a professional audio engineer & mixer) and I determined that was about as close to "flat" as we could get. The PM6004 and the PM8804 were left in "Source Direct" mode. Yes... it makes a big difference having it on. I was surprised at how much so.
My room also has a bass hang right around 60 Hz (and consequently 120 Hz, 240 Hz, etc.) due to the room dimensions. Not much I can do about that (short of putting in bass traps). This will also come into play.
I tried to stick to recordings that people might know. I used Miles Davis' "So What" from Kind of Blue , Fleetwood Mac's "Sara" from Tusk, Brian Eno's 2/2 from Music for Airports, and Karajan's recording of Beethoven's 3rd (the digital DG recording from the 80s, not from the classic DG cycle in the 60s. For analysis purposes, this recording is more revealing.)
"So What"
1060: Although it sounds like a big room, you are right there up front. The horns are basically blowing in your ear. There is room reverb, but it's more after the note, not present from the initial attack. The bass is not the most detailed, but it's there and musical.
PM6004: More sense of depth. You can tell just how big the old Columbia studio that was previously a Greek Orthodox church really is. The musicians sound further back. While the detail is nice, the sound seems a smidge analytical.
PM8004: Wow. This thing has a gorgeous tone. It is much darker than the PM6004 and does not feel analytical at all. You can tell there is so much more current driving into the speakers. There is also way more information in the low frequencies than the other two (which can sometimes be problematic in this room). There is a real organic quality to the sound without giving up a sense of depth. That being said, right when the head ends and Paul Chambers really digs into the notes at the beginning of Miles solo, the bottom end got a bit burly (again, probably my room acting up). This thing is dark, but I'm into it. It's quite seductive.
"Sara"
1060: The drums are right up front. The mix sounds amazing. You can't help but feel like this album was made to be listened to on something like the 1060. (Duh...)
PM6004: Way, way, way more depth and soundstage. Everything is pushed back and you can hear the reverb and delay tails all over the place. Nice separation of God knows how many tracks they put on this song. The soundstage is huge, but seems to lack a real anchor (if that makes any sense).
PM8004: It seems to split the difference between the two and feels great. There is that warmth and hump to the drums that the 1060 just nails, yet there is a much bigger sense of space. While this sounds fantastic, and I love it, the mix feels most right on the 1060. (I could go on, but I will spare you.)
"2/2"
1060: I always think using recordings of analog synths can be very revealing of detail and how a component is voiced, sometimes more so than strings. The 1060 actual did not shine as much as I had hoped here. It is warm and inviting, but you cannot hear the detail and the grain in the synth sounds. The contrast between the different textures on each synth is not as apparent as the other two amps.
PM6004:
You can hear the texture of each voice nicely, but it does not put me right there. I spent a lot of time with one of those giant patch-bay Moog's in college and this doesn't quite get it. Still, it's pretty darn close.
PM8004:
Jaw on the ground. It may be a TOUCH dark, but oh my, this thing nails it, nails it, nails it.
Beethoven's 3rd:
1060: Sounds great, but the orchestra does sound like they are sitting on top of each other a bit compared to the modern amps, but, I kinda like it. IT is very engaging.
PM6004: Very bright with this recording. Interestingly, the PM6004 seems to be the least forgiving of the three in the high frequencies; however, this is a bright recording and it's not obnoxious on the 6004, just very... detailed up there. Nice dynamics, but the basses seem to be lacking a certain something in the upper bass/low mid area.
PM8004: This thing has tons of power. The dynamics are unreal. Almost problematic really, considering I live in an apartment. These crescendos sweep and swoon. The basses are sawing away at you. Again, it is dark, but it is really working with this recording.
My two cents:
The 1060, I have to say, sounds pretty nice compared to these two modern receivers. Its charm is that it puts everything very up front and sounds very natural and organic. That being said, it does not have the same sense of depth or detail as the modern stuff. It's most notable on the tale end of notes. On those old jazz recordings, you can't hear the slight rattle of cat gut stings when the note is released on an upright bass as well as you can with the more modern stuff. It nails the transients in a great way, but the reverb and delays at the end of notes/hits are somewhat absent. This can add an intimacy, though, particularly with jazz and rock.
The PM6004 is great, but I think if I had to choose between spending money on the 6004 or getting the 1060 recapped, I would get the 1060 recapped. What the 1060 does right, it really does right. I can live with a smaller soundstage and a little less detail if I feel the music sounds more organic and moves me more.
Now, the PM8004. (Thanks Art K. for insisting that I check it out!) What can I say? I really love this thing. It is a bit boomy in my room. Sadly, turning off the direct source mode to dial back the bass looses some of the magic. The bass is intense on this thing. When I buy one of these, and I will get one, I might have to look for a speaker cable that is a bit leaner in the low end. (I never thought I would say that.)
Anyway, sorry for such a long post. Just thought I would share my observations.