Audio Hungaray Qualiton A50i vs LTA Z40+ Integrated

I should add that the Ifi streamer is a transport only -- it doesn't have an internal dac. If you choose that one, you'll either need to buy an external dac (usually the better option) or get an integrated amp with a dac built in. Of course, the cost of an external dac changes the price calculation. If you have the cash, I'd recommend the Denefrips Ares II Enyo for $850. Their dacs to me sound more natural and "undigital" than similarly priced chip dacs. (Switching to Qobuz should also help in that area. I think it sounds more natural/less digital than Tidal.)

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.

Given your stated tastes it would seem the AH Qualiton would be the better choice although it’s really hard to see going wrong with either, especially when you factor in tube rolling.  You’re in for a treat, but please get your source sorted out first.  I mentioned the iFi Zen Stream because it’s very good at its price point, but if you can stretch a bit by all means go for the new Innuos Pulse Mini as it’s better on all levels, and Innuos actually provides great customer support, which iFi definitely does not.  

Minimum impedance for those Focals is 2.8 ohms, will be a very tough load if the attending phase angle is steep and if this minimum is in the bass frequency range (which it most often is). The two amps you are weighing have power ratings at 4 ohms that could be an issue IMO. You might want to consider a hybrid integrated (Copland makes a good one) with a solid 4 ohm rating OR ditch the Focals for the  new Mofi Sourcepoint 10s, that way you could be sure the amps you're weighing are gonna flourish (if your room isn't big at least).

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!