Let me gather all the things I need to do once i get back home....
- Rca inputs clean
metal jumpers clean with alcohol
speaker cable re-terminate
Clean the DM4 fuse holder
Kindest regards
helium
A good clean is always good!
Also, a good de-gauss is something I also feel is prudent on older systems...
Densen De-Magic, it's a cd that you play in your system, that will work magic with the system.
What it does is set up a reverse polarity magnetized signal in the circuits and demagnetize the print and components. Rather unique this cd! You play it say 5 times fairly loud the first time, then say once a week, and then you play the 3minute track lower and about 2 or three times in a row.
The track does sound absolutely horrible, it's a sort of strange hum noise in 3 levels.
What it does is that is sort of makes you components "sonically" younger... It's a great product!!!
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As for the JBL's I agree, they are good for rock, so if you can get such a speaker, I'd opt for those over what I wrote, more LF reach, more punch.
I suggested more large bookshelf's and those some times like more power to really sing than a floor stander.
Now on the subject of bass warmth, there is a matter also...
Because ... once you hear a speaker that really can kick and resolve the important powerrange of music "250 - 60hz", any and all improvement here also help toward a more pleasing bass experience...
So bass warmth might not be what you are really looking for, but one could almost say that you are looking for a better "power range " in your speaker. If the speaker in addition can go down to 35 -45 with this clarity and punch, ok, now we are talking good bass!! I believe the JBL 880 and others will do this.
It's 90.5db in sensitivity and about a 4 ohm design I believe. You will be able to play "rather" loud with it I think. The 880 is also front ported, and that can be important for that "punch" sensation in the sound, playing rock...
The frequency range from say 34hz and down are primarily used for spatial cues, what this means is that those frequecies define the recorded space, as reproduced by your loudspeakers.
And in a "rock" speaker, those are not really "needed" ...
So when looking for a good rock speaker, it could be importnat to remember that you don't need it to go down VERY low... you need response and punch, and preferably clarity down to about 40hz, or so, that will suffice nicely!
If you are by now feeling particularly tweak happy, I've got more ideas...
I'm on a roll here so i'm also gonna mention what could be an improvement for you in addition.
The Musical Fidelity X10-D tube buffer. I'm not gonna say more about it, than that it exists.
Check it out and read about it if you want. It will complicate you set up somewhat, and should only be looked at very last in a round of upgrading, but it might be worthwhile!
It will "warm" the sound you see...
If.. you for some reason are contemplating a new set of speaker cables down the lane...
I have a suggestion for that as well.
Audioquest CV-4 with 36/48volts of di-electric pre-bias. It must be "powered" for say over 36h for the effect to really level off and start working...
It's fairly cheap... about a little under 500 us dollars for a 10 foot pair. (from $200 without the bias system)
And I think that this cable is a bargain, considering what it can do for an "older system" ...
my 2 cents...
I'm gonna be so bold as to say that after cleaning the system, and densen de-magic'ing it, a set of at least "standard" Audioquest CV-4's will do wonders for the about 200 buckaroo's this will set you back. You might wanna do this, before adding new speakers also..

What kind of track would I have used to assess all of these "tweaks" I'm suggesting?
Lenny Kravitz - "I belong to you" AND/or "American Woman". These have a nice blend of bass, attack and decay and harmonic content within the recording. Great for tracking what is actually happening sonically!
Also Mark Knopfler's - "Sailing to Philadelphia" album. It is soooo "complete" in it's harmonic content I feel and will give you a great indication of how your system is able to convey "emotional impact" in music. A very well recorded album!!!
Great for assessing "tunefullness", "pitch accuracy" and so on in the deep end too!
Imp.