Gotta go with Rocket on this. The Eastern Electric DAC has a faceplate button that lets the listener switch, on the fly, between the solid state output and the tube output, which is a very nice feature, IMO. The DAC is not a high-cost product, depending on one's budget, of course, and they were several used units for sale here on AC, although they are a little more than $500.00 but arguably worth a little extra expense. Just my $0.02 in case you reconsider.
For a budget and/or spare DAC, the JDLabs ODAC (under $170) might be a consideration.