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
I recently got the Topping D70. It not only bests my Oppo BDP-105D but has completely changed my concept of how good digital playback can be. Right now, Drop (Massdrop) is offering them for $400.
OP, I have a Shek D2 (Sigtone) non oversampling Dac I bought new for just over 300 which has been used less than 100 hrs and a HagUsb converter that I bought new which cost 130 .. (Hagerman Technology)   would sell both for 200.    Went back and read more of your posts.   Schiit should work out and assume they have USB interface.  Wonder how Schiit compares with discontinued    Shek D2 ..   

both are listed -- on US Audio Mart.
Wanting to move some stuff out of here.

see my feedback on here.