Low Cost DACs


Currently I have my laptop connected directly via 1/8 jack from headphone outlet into 2 RCAs directly into my tube amp. Quality of sound is lacking to say the least!
I am considering adding an inexpensive DAC ( iFi AUDIO nano iDSD LE Portable DAC  or iFi Audio nano iOne DAC ) into the stream between the laptop & amp.My question is: will this influence the overall sound I'll hear out of my speakers? Will adding such a DAC help to increase the quality of sound produced by the system?
I'm not interested in spending a lot of money on a DAC as this is a source that I don't use as much as some others already in the system.
wcc10
Musical fidelity v90 dac, $299, and worth every penny. Beats out dacs costing way more. Very well reviewed in stereophile and they gave it a borderline class A component rating. To be honest, all the small box components from musical fidelity are fabulous, including the lx lps phono preamp & the lx2-HPA headphone amp. 
Check out  Wireworld. I use the Chroma. I bought a 1 meter length for $30 new. A great cable for the money. I use mine with the Modi2. 
speaking of USB cables, I've only used Schiit USB which is Straight Wire. anybody try something and found that it was worth getting over the Schiit USB? 
I'm using the ifi nano LE to my preamp and I'm very happy with it. I have a Schitt Modi Multibit and a Nixon dac I like to try affordable dacs to see what I like but I'll never be a player in the >$1000 range so these will have to do. The thing they all have in common is they're musical and they're paid for.