I was very hesitant to post here, as I'm usually unsure which end of the chain (the TRANSDUCERS!) to change first. But I'm damned-sure it shouldn't be the amp! I'd lived with those same big NAD amps for 10 years, and borrowed an Audio Refinement Complete integrated to quickly compare. Well, the difference was substantial, but of course the big NAD had more headroom, which might be needed, depending upon the efficiency of the speakers I might have selected. NEVER buy an amp until you've finalized your speaker selection (sorry, KT88).
My upgrade process started with finding the best speakers I could afford that sounded great IN THE ROOM! This was the hardest, and LEAST predictable part! Once accomplished,
I soon heard MORE digital artifacts from the old Rotel 855 CDP, as well a lack of transparency from the NAD preamp.
The borrowed ARC Integrated smoothed things out, but lacked sufficient bottom end for the 4 ohm woofers in the selected speakers (Parsifal Encores).
I tried bigger power amps (Acurus) as well VAC tubes (WOEFULLY non-linear!), and finally settled on used Aleph 2 monos, which had great slam and an utterly beguiling midrange with the Encores. Next it was clear that the preamp was too veiled and dirty, and Alephs are a bit tricky to drive, so I chased a used Aleph P. What silence and soundstage! Now the amp/speaker chain was perfect! Nordost Red Dawn XLR and cables worked fine.
Of course the now GREATLY exposed digititis of the old Rotel 855 was overwhelming on most Redbook, so I performed a year-long set of comparos between the Rotel and: ADCOM (lacking musicality), ARCAM 9 (lacking PRAT), the ARC CDP (too rolled off up top), and the Bel Canto DAC (WAY too lean and white-hot up top!). This was getting exasperating. Then I followed a few suggestions and tried an EC EMC-1 MkII, and was astounded at the result! Everything then fell into place! After a while I decided the system was still a little too lean on MOST less-pristene
CDs, so an IC search filtered out the Red Dawn, HT Pro-Silway, Siltech, and finally found an ideal match with the Discovy Essence. Screwing around with dedicated AC and PCs lately has been nice, and maybe is giving me that last 1-2%. I'm not sure. Doesn't REALLY matter, although we all chase the holy grail, eh?
My point here is to note the upgrade path. Yours may mirror mine....
Knowing a bit about old ADS and Braun designs, I imagine that your speakers have a woeful "saddle" shaped curve, with an uneven, hot treble, and a loose, over-ripe bottom; your pre, as suggested earlier, is not really transparent; nor is the 2600, but it'll do for now; the CDP I don't know about, but probably sounds flat, hifi-ish, etc.
Changing ANY of these components first might give you a decent improvement, but you want to try to reduce the chance of having to change the same part more than once!
I NEVER would have known the bass slam of either the speakers nor the CDP if I had kept that ARC integrated, as nice as it was! If I had been satisfied with the ARCAM 9 because it had a great midrange and cleaner treble I would have never noticed it's two left-feet until the speaker/amp chain was installed.
I understand those that suggest you use the GIGO route and start with a new source. That would probably work.
Nonetheless the variability of speaker-transducer and room-loading permutations is VASTLY greater than that of sources , amps, or cables, so I have to recommend that you
start your hunt by finding much smoother, musical speakers that sound great IN YOUR ROOM! Don't worry TOO much about fine-tuning the damping until you get the other components in place, but do make sure you have a fairly even frequency response that pleases you. Yes, your pre and amp's shortcomings may come into blatant obviousness, as SURELY will your CDPs, but then you can do things in the order I suggest worked efficiently for me: find the amplification that makes that speaker really work best (it might be even a nice EC4 or a cheap ARC, or whatever separates you like) and THEN chase the most musical front end you can find. Finally use cables to
filter the spectral tilt to your liking. The odds are that you may then only replace one item again, and if you're luckier, like me, you'll get it right the first time.
It took me two years, but assembling a $30k system (for $17k used/demo) that I probably won't upgrade for at least a decade has been VERY satisfying. I'm grateful to the many A'goners and dealers who helped along the way.
Use your ears as the best judge, and take your time...especially with speaker selection. I know that lugging speakers home to set up listening sessions is a lot of work, but believe me there's no other way. The subsequent decisions can be just as difficult, as many artifacts will be more subtle as you go, but at least the demo-ing will require less weight-lifting!
Have fun, and continue to ask questions along the way.
Ernie
