iFI GE5670 + Special adapter Stemming from the R&D work into the development of the micro iTUBE, the NOS6922 matched tube pair is another ‘atypical’ product from iFi that significantly improves the audio experience. For any tube/valve audio product from amplifiers to CD players that use the common 6922 tube/valve, the premium NOS 6922 matched pair set is a straight ‘drop-in’ replacement.