A quick comment about the TA-01. I purchased one a some time ago and subsequently posted some pics, in this forum, which show the pair of CS-4398 chips inside. I sold that unit and quickly regretted it. So, I've since re-purchased an identical unit.
My primary headphones often get heavy after long sessions so I like to wear the K7XX for casual listening of news-clips, youtube, etc. I keep the very light K7XX's plugged into the TA-01 for an outstanding setup I can wear and enjoy for hours. I plan on keeping the TA-01 to compare against other dac/amp combos I buy & sell.
My overall impression from the TA-01 is indistinguishable, to my tinny ears, from the Fiio E17K/K5 combo and even the Fiio X5iii/K5 combo.
The presence & punch of my Mojo/CTH combo is in a different league than the TA-01 but so is the cost.
The TA-01 is easily worth the $119 you can get it for in this drop or elsewhere.