To preamp or not to preamp?

I am pulling together a two channel system that will also have a home theater function. At this point, I am only going to have one source- a CD/DVD player. I have noticed a few source units (such as the EAD DVDMaster 8000) that are able to connect directly to the amp and eliminate the need for a preamp. I am trying to understand the pros/cons of such a configuration. Does anyone out there have experience running a system without the preamp that they would like to share? System is under construction and so far includes Quad 989s as mains with dynamic Quads to cover the other three channels and a Levinson 334. I am looking to spend less than $4000 for the source unit.
I haven't used a a re since I got my first Wadia.If you don't need it then why have it?
There are pros and cons to each option. I generally preferred running my Opus 21 CDP through a preamp because it was more full-bodied and dynamic while direct it was less veiled, cleaner. The Wadia's built-in volume control appears to be designed well for the purpose of running direct. I don't know the details of this, just read that they took into consideration.
this may not be the most conclusive response, but i am in the same boat as you. i recently purchased a cairn for cdp that allows you to run amps directly. i also purchased cairn's nanda preamp and mea monoblocks as well. the fog is currently powering the meas directly and i am absolutely loving the sound! (possibly more than with the preamp in the middle, and it is a fine preamp for the price). like budrew comments, there are differences, and very noticible ones at that, it really depends on your personal preference and system synergy to determine if you 'need' a preamp or not. i have not conclusively ruled the preamp 'out' of my system, but may be on the verge of doing so, and possibly never looking back? (i aspire to the likes of kenscollick's wadia based system above ;) ) but i can only suggest that you listen to your system both with a pre in and out, i believe you will find the experience interesting if nothing else...
The only pro to going passive is saving money period. If your budget is over 4grand then even the best passive company out there agrees and promotes that active is allways better. Check out placette audio for conformation of the concepts at work here. All the placette passive owners that have gone to the active placette stay with the active- it's only a money issue and anyone that says otherwise just values spending their money on other parts of their system which of course is right for them.
I went from mega-buck CDPs and DACs ( Wadia, DCS, Chord, Audio Aero, MSB, Bel Canto ,etc ) to my all-in-one solution -> EAD 8800-Pro pre/pro. I have owned several EAD products in the past too.

The EAD 8800-Pro really gives me great 2-channel sonics, and I do not feel I am compromising much in either 2-channel or HT.

And I just inserted a Monarchy DIP upsampler between by CD transport and EAD, for even further improvement for my 2-channel. I use an SDI mod'd Panasonic XP50 DVD player for my HT duties.

Another 8800-Pro owner says that the current 8800 series is easily sonically superior to the previous 8000 series, FWIW.

EAD have been really good with software updates too.

Another CDP I really like is the Classe CDP-10, mated to a Placette passive or EVS attentuators. The Classe has plenty of output voltage to run passive.

- Andy
I was using a passive pre for 4 months, I was really happy. Then I tried a tubed pre to see what I was missing. There's no going back for me, the difference was very prominent. With the passive pre, the sounds was very detailed, but it sounded thin. With my pre in place, the sound is fleshed out, harmonically richer as if going from a color pencil drawing to a color photo. You have to wonder why there are so many $$$ preamps offered. I am listening to the Emotive Audio Poeta now, I can only drool at the thought of hearing the new Epifania. If anyone has heard it, please post your thoughts.
IMO, doing away with the active pre will be beneficial (unless you go for a giga$ active device).

HOWEVER, there are two considerations if you bypass the active pre:
1) the quality of the attenuator /volume pot (whether it's the cd/dvd's or a stand alone)
2) matching the output impedance (of the dvd or stand alone attenuator) with the Lev's input impedance.

If the impedances are NOT matched, you won't be transfering the signal well enough to the amp (much of the signal will be lost) and, typically, you'll notice a loss of energy in the bass/low-mids (since that's were there's more energy). So the system will sound "thin". OTOH, a good matching will give you a lot of detail and a well balanced response.

So if you're interested, don't dismiss the passive option unless you know that the impedance matching is there. Any dealer or manufacturer of attenuators should be able to steer you in the right "matching" direction.
The old passive/active question again. I love this. Of course, running a component direct is not really 'passive', but there are the same principles. I have discovered there is more to it than output levels and impedences.
I got a quicksilver pre, partly because it has a high quality attenuater, that with a simple rewire, I made into a passive, which was identical in every way to the active part, same parts and jacks and wires, just bypassed the active pre. I was able to try both with a number of source components and amps. While there are cases where certain matches between source and amp just didn't work because of input/output impedences, the output level, or the attenuater, I discovered that a lot of source components that had specs that should have made a passive work great worked better active and visa-versa. While adding something in the chain is always a comprimise to the preservation of the signal, Some components put out a better signal to begin with when they are into a pre. Besides the obvious loss in bass, or dynamics, or 'omph', that indicate a loss of signal, when there is no 'loss', you could listen to how transparent and accurate the sound of a component is when driving a pre.
While it it is important to consider the specs, and they do matter, of the components you are matching, I think you should listen yourself to the components you are going to use, and not rule out the possibility of going either way now or in the future.