I think it really depends on how you want to tilt the sound toward. What do you like about it right now, and what would you change about it? Just to narrow down what you’d be looking for. And generally what sort of budget would you be looking in for a new DAC?
Tube wise I’d check the quicksilver thread on here since there’s some good info on what tube pairings were good options. Cable wise, we also have a good list of options in the more budget cable thread (although when it comes to cables, I’d likely only explore that after you mess with tubes and/or the dac)