Seems like you should either upgrade the speakers and/or the DAC.
I have the Lektor 1s (on the end of a Sugden Mystro amp and V-dac/psu/link). They're great for near field listening, on or close to the wall, and unfussy about placement. The Lektor 1 definitely benefits from quality sources and amps.
£500+ could also get you a seriously good DAC. Speaking from experience, I'm not sure I'd sink too much cash into the MF v-series, though it does a fine job for a £200 DAC. The v-psu is an improvement, but if you suspect that in the long run you're not going to be happy with the v-dac, IMHO you're better off stepping up to a better DAC than trying to improve a budget one.
Since your system is fairly portable, why not take it all down to a dealer who stocks the Lektor 1's and listen with these, and compare with some other hi-end speakers and/or DACs/sources?