2 channel system?

I'd suggest going with amp/preamp first. I only say this because it is good to see what the source you currently have can sound like. It's hard to judge sources with bad preamplification/amplification. Get amplification/preamplification that matches your speakers.

KF

I agree with amplification first, and if separates, the preamp before the power amp. What good is a great source sent through inferior amplification.

I also agree with the cable comments. Most people put a cheap cable on a lower cost source. You'd be surprised how good a lower cost source will sound connected with better cables.

You said that you wanted to upgrade the integrated amplifier and did not wish to go with preamp/amp.I would suggest you get one of the following: Rowland Concentra I or II,Gryphon Tabu Century,Gryphon 2100 or 2200,YBA Passion Integre.Do not stay in the middle,no source will help you achieve a good sound if you do.Then try different players and judge them accordingly.In the beginning this may sound like a waist of money but in the long term,I think,you will be pleased.CD-players come and go,good amplification stays.That's what I would do.

I've no quarrel with starting with the source. I would caution against starting with amplifiers, at least until you have selected a style of speaker. Will you choose cones, planars, electrostatics ... monitors, full-range .... a subwoofer ...? These choices will have a huge impact on what amplifiers will be necessary and suitable, let alone preferences among them. At least the source components are pretty much free of this critical interdependency.