I agree with the others who are saying that the first thing to upgrade is your streamer/DAC situation before upgrading amps. That is a lofi solution you're using with ifi and your phone.
Having said that, I have the Qualiton 50i and it is amazing. Musical, holographic, and very powerful. I happen to have it paired with Audio Solutions Figaro M speakers. That's a perfect match because Audio Solutions uses the Qualiton 50i to voice their Figaro M speakers. I have also run Harbeth S-HL5 speakers on this amp, and I have never heard the Harbeths sound better.
I am not familiar with the LTA amp.