I too owned and loved the Qualiton a50i. I replaced my Luxman 590AXII with the Qualiton and couldn't be happier. This is one amp I will gladly buy again for my second system when the funds are available. As someone here mentioned, it is powerful, musical, and holographic. IMO, it really does a great job of creating a lush, full, holographic, airy sound without getting too tubey or syrupy. Great execution of pure class A with classic tube sound!
The a50i drove all the following speakers in my listening room quite well -- Harbeth SHL5+, Fritz Carrera BE, and Joseph Audio Perspective2. Although, it did struggle just a little bit with the Joseph Audio with respect to reproducing the lower frequencies, but the JA is not a particularly efficient speaker to begin with.
I have not heard the LTA, but from what I read it is more on the neutral side compared to other tube amps. Best to audition both if you can, but in either case the AH Qualiton a50i is a fantastic amp that will make you very happy!