Does the Transport make a significant difference?

Had been running a squeezebox with my Audio Note 2.1 Dac. Tried my basic Oppo dvd player as a transport and yikes what an improvement - even over my $3,000 invested Modwright Sony player (a little rough round the edges but dynamic and live-ly sounding). So wondering if the mantra of having a great source is the best place to start ... ie matching the Dac to a quality transport say CEC TL 51 or open the vaults and spring for a quality Audio Note, Esoteric, or even dcs transport will be worth the investment. How does this compare with say upgrading your amp or speakers or even cables? I know I should listen for myself but any good experience out there to draw on before I start getting crazy about checking out the used adverts?