06-12-12: Mingles
A great sounding low-cost preamp that mates well with the DL-103 is a Jolida JD9. They come up used in the $300-350 range. List is $499. There are lots of well documented tweaks to improve performance to a much higher level.
I was just going to suggest that. In fact, I upgraded from a 640P to a JD9 about 1-1/2 yrs ago and couldn't be happier. The gain and sensitivity levels plus the wide range of capacitance (for MM) and resistance (for MC) enable you to dial in a near optimum load and gain setting for just about any cartridge. It also has a "grown up" power supply and tubed buffer stage. I think it will wring a lot more performance out of your 103 without having to get into stupid money. Mine always strikes me as musical, organic-sounding, nicely transparent, exteneded at the frequency extremes, and never harsh or edgy.