ok, now i just need to pick one

i'm looking for a new amp/ preamp, which one is best used: acurus dia 100, cambridge audio a3, or nad c520? does any one know of any amps similar to the acurus that can bypass the use of a preamp?
I am in your other post. I use a Cambridge A3i in my home office/den. I have not heard better at that price point; and I've tried a lot of them including NAD, which are also pretty nice, just not as lively as Cambridge. Plus the A3i has a decent phono section, if you want to play with vinyl. I have listened to Acurus; very nice for the money, but it did not convince me to replace the Cambridge which is a lot cheaper.
I would guess that the acurus is "better," but how old is the one you're looking at? All of these components impose some coloration and choosing one without knowing your speakers or source (I assume cdp) it's just difficult to say. I suggested a NAD integrated in your other thread because they do seem to mate well with a lot of speakers. But the acurus actually gives you a taste of high end sound.

I have never heard the Cambridge, and it may be as good or better than the NAD. You'd have to listen to it. I bought a NAD because I was troubled by the Cambridge's large markup from the UK price to the US (even tho made in Asia). The NADs retail for about the same here as in the UK.

In your other thread someone suggested a demo Cambridge piece from Audio Advisor. If new unopened and they're just clearing something out that's fine, but I assume that their "demos" are units returned by buyers who decided not to keep them under their 30 day trial policy.