money best spent on better dac, transport, preamp?

I have good speakers and amp in B&W 801 matrix and levinson 27.5 but think I should have better results. My transport is a Parasound cdp100, dac is aragon d2a, preamp is Marantz 9000 preamp/processor. Which should be replaced first to hear a noticeable improvement?. Budget is $1000 for each used. Thanks for any help.
Dump the CD, DAC and preamp and spend the combined $3,000 budget on a recent vintage CD player with a volume control. Wadia comes to mind, but there are others that fit the bill.
Are you sure that the ML 27.5 has the power to drive the 801's? That is only 100wpc. How big is your room?
I ask, because I used to have the ML 27, and when I got my Revel Studio speakers, I upgraded to the ML 23, (200 wpc). The sound is better, as it has more dynamic headroom. Just a thought.

Also, if you are going with onhwy61's suggestion, (and it is a logical suggestion), you might want to look at the Resolution Audio Opus 21 cdp. I have one being delivered in a week or so. From my research, it is a bargain at the price. (New=$3,500).

Good Luck!
Your digital setup looks like it could stand a little updating to bring you to greater heights.

I owned the Aragon D2A mk2 and while it was good, I found it easily forgettable when replaced with even modest modern equipment.

I did a direct comparison between the Aragon D2A mk 2 + Marantz CD5000 (the same base unit they mod to make the Ah! Njoe Tjoeb, but by itself not very hi-fi) vs. my previous player - the Music Hall CD25 ($350 used), and the onboard DACs of the Music Hall sounded just slightly better than the Aragon + Marantz.

The onboard DACs of my Rega Planet 2000 ($550-$600 used) were even better still than the Music Hall's. Combined with a Bel Canto Dac 1.1 ($500 used) and Sonic Frontiers Ultra Jitterbug ($200 used), the Rega/Bel Canto/SF combo just demolished the old Aragon. So you can really attain multitudes better performance for not much money - such is the nature of digital: after a few years, the old hi-fi digital really sounds "old" compared to reasonably priced new hi-fi digital.

I also find that phenomenon sufficient justification never to spend megabucks on the digital frontend... there's lots of depreciation here. Your budget and expectations seem safe from the worst ravages of depreciation in this category, and should buy you nicer equipment than I've described, and who knows how many more steps better sound. There's lots of room low-to-high in this category, performance-wise.

Best of luck,
The first response to your post is really right on the money. Of course this will not work so well if you still spin vinyl. My suggestion is the Audio Aero Capitole Mark II Cd player that has all of the things you want and it is available used here on Audiogon for a bit more than your budget. I run my DVD player, my Satellite and my multi-disk Yamaha CD player through it.

the latest version even has an analog passthru so you can run your tuner through it; the older versions are upgradable to the analog passthru.
Check out a used Cal Audio Delta transport and Alpha DAC; wonderful units for way less than a grand used.
Trade in the marantz. You have a lot of wasted technology shoved into a box that you want for stereo listening. It's not a bad pre-amp, it's just that it is designed for theater. Sell the Marantz and get something designed for stereo listening. With the big boom in surround sound, you should be able to get a nice deal on a good used stereo piece like classe, audible illusions, CJ....

By the way, to test your d/a, try going digital from the cd to the marantz and listen to the differences?
Cary 303 CDP has vol control on the remote and is my fav for CPD for under $3k. If I had to do it over I'd have the Cary CDP going directly to an amp. If you have a local dealer try to get him to let you demo the Cary 303 (most dealers sell it new for ~2400). You can always buy a better Pre/Proc, but oh what a better CDP can do...