NO, it's not always necessary, whether it will be better is a question that cannot be answered in general though. It will critically depend on whether your cdp is a good match in electrical terms with your amp and, of course, the individual as well as relative quality of your cdp, amp AND the pre-amp you intend to use. I would avoid the direct connection if the volume control is in the digital domain, though (unless you go Wadia, phew, narrowly escaped stoning there).
Your consideration on going for first class cdp and amp now and, perhaps, adding a pre-amp later looks optimal to me. Remember you also save the immediate cost of one more IC and one more PC. And it's not only a consideration of cost, but also an interesting adventure in audiophilia, I would have thought (I am experimenting presently with a Ancient Audio Lektor V fed directly into Kharma Matrix MP 150)
I bet those sales reps all had the ideal pre-amp to sell to you, huh?
Your consideration on going for first class cdp and amp now and, perhaps, adding a pre-amp later looks optimal to me. Remember you also save the immediate cost of one more IC and one more PC. And it's not only a consideration of cost, but also an interesting adventure in audiophilia, I would have thought (I am experimenting presently with a Ancient Audio Lektor V fed directly into Kharma Matrix MP 150)
I bet those sales reps all had the ideal pre-amp to sell to you, huh?