Are you serious? The ADS speakers are MUCH better than the HPM-100s, it's not even close...
The hpm-100 were designed by the same team that designed the jbl-100. Having owned both, my opinion is that the hpm-100 were better. Better bass punch and more dynamic. These still have a following 35+ years later. No, they are not accurate, but they are a lot of fun. I think they are just what you are looking for.
ricplaya, when you speak of complimenting the ads 570, are you talking about running another pair of speakers in order to augment the bass? if so, i'd simply get a sub, which will hightlight rather than murk up the high frequencies. if for some reason you feel compelled to run more than one pair of speakers, i'd stay in the ads family so that at least the drivers will have similar sonic characteristics. as for the hpm100s, i own some and (like jig) think they're tons of fun, if not esp. accurate.
The HPM-100 is a boom'n'sizzle rock/pop loudspeaker. The L-1090 (I owned a pair for 9 yrs and they anchored my main system) is a serious loudspeaker that can kick ass on everything from rock to acoustic pop, jazz, thrash, large scale orchestral, chamber music, big band, you name it. They also do a great disappearing act and image like mo-fo's.
Whatever you like from the L-570 the L-1090 will give you much more of it in terms of clarity, dynamic range, and frequency extension. To put it in perspective, the ADS product line of the mid-'80s included the L-1590, L-1290, and L-1090. They were all sealed cabinet twin-woofer towers with dome midrange and tweeter. All three models shared the exact same midrange and tweeter and varied only in cabinet and woofer size. The L-1590 was Telarc's monitor of choice at this time.
Given that the L-1090 is a sealed cabinet design, the bass is not thumpy or especially strong, but it's there and is very musical, quick, and well blended with the upper drivers. I also got much better bass when I upgraded to a 200 wpc high current high damping factor power amp.
So I can't give you advice on which to get because we don't know how you intend to use the second pair of speakers, so instead I'm trying to share what you can expect from the L-1090's. The HPM-100s will probably sound stronger in the bass because it's a 12" driver in a ported cabinet, but I suspect that the bass will mostly be a thump at around 50 Hz and drop off quickly from there. The ADS will have audible bass down to at least the low 40's and maybe lower depending on room placement.
My Marantz and the 1090s sound pretty sick. Image like a mofo is right. The music sounds like it's coming from the record player across the room. I experimented with the speaker placement a little bit and found the sweet spot and it's magical. I can see with these it's all volume and less eq, they do sound richer with the more juice you throw at it. They are a completely different animal then the L570s, there is no reason to run anything else with the 1090s. I can't imagine if they were bi-amped how good they would sound!
Except that it would take significant mods to bi-amp the L-1090's as they come with just a single pair of terminals. Better to spend the money on a good pair of speaker cables and a high current amp.
Also, since the columns are so narrow, it would be good to get a set of outriggers from Soundocity. I bought a pair of ADS's own optional wide-stance bases for the speakers, but that was in 1988 and I lived near their factory. They'd be very hard to find now. The wider stance was helpful so the outriggers should be even better.
I have more stupid questions.... Go figure!
Johnny appreciate all your expertise. I run 2270, so you think I need more power? I can just run the Marantz into a high powered amp, like a pre-amp?
I was thinking about the bennefits of a phono pre-amp, but your suggestion would eliminate that? I really like the warm phat tone of the Marantz. If I got another amp, wouldn't that really change the tone?
If you like your Marantz, stick with it. The 2270 is a fairly hefty unit with enough power and current to drive the L-1090's well, and that generation of Marantz had good tuners and phono sections.
And yes, you can still use the Marantz as a tuner/preamp for a separate power amp if you'd like, because--unlike most receivers--the 2270 has pre-amp outputs on the back panel. At present they're jumpered to the "main in" (amplifier) section, but you can remove the jumpers and connect the "Pre-Out" to the inputs of a separate power amplifier if desired.
For now enjoy the features and tonal balance of the Marantz. It provides multiple upgrade paths should you later want for more power and/or bandwidth. I think it's a good idea to get used to your rig one component at a time, especially when dealing with vintage equipment. I anchor my 2-channel LP-based system with a 1981 Heathkit power amp. A few years ago I was using a 1980's Amber amp and preamp, so I'm familiar with putting together a system piece by piece with vintage equipment.