Upgrade from a Sonic Froniers CD-1

I'm thinking about upgrading cd players.I'm not sure of the sonic differences between my player and some of the ones I'm looking at.The players I've been looking at are the Ayre,Audiomeca,Cary,Audio research and Wadia.With recent additions to my system like the Pass x-600 & x-1 preamp,the sound I thought got a little sterile.I'm after a smooth non-edgy sounding player that would compliment well with my Amp &Preamp,(maybe a touch of thickness to the bottom end).Also my budget is About $4000 new or used...Any comments would be great.