1) No radio channels won't change when screen is turned off. You cannot preset more than 30 channels. There is not instant RDS feature like on cars. Can't adjust the EQ features while on Radio. But on screen buttons provide much quicker reaction than normal music player controls.
In short don't buy this device for practical Radio usage.
2) Sound was quite dissppointment for me. This is the 1st time head fi fooled me big time. Excellent hardware with A35 but my S7 exynoss can give lower frequencies than A35. With A35 bass is boosted, treble is boosted. I'm sick that Sony does the same tuning to their smartphones like all Z series, many headphones like MDR1A and now to this A-35. And It's quite frightening that only few recognized this so far. Everybody here says wow really good, cymbals are great, player is a bit warm and all that but I can't get over that Samsungs and iPhones sound almost dead flat but not this player. And that's the elephant in the room, really obvious. Clarity and black bacground is very good however. Very good hardware. One other problem with me is that soundstage feels compressed into my head. Layering is good but all is compressed into my head, S7 iPhones and Soundcards (Xonar U7 I have) don't make me "uuh enough". I want more with them mostly but not with this player. I usually listen on way lower levels with this A35 player because of that problem. BTW If you listen mostly dubstep and EDM you might find it to your advantage.
3) This player is SLOW. Because of Processor and in built storage. Sorry but If 2007 iPod device is more fluid and instant reactions to your presses and not 2017 device, there is no defending it. HOWEVER, many quality Daps have this problem (except some flagship ones) I use mostly device Storage, even with the no album art files It sttters almost all the time while scrolling. Worse than 2012 android flagships. BUT I don't know how it will effect If I insert better than class 10 SD carda and transfer all the files to it. But, screen is quite good. I wish there was light sensor. Screen responsivenes not that great also. Some smudges will confuse the touch responsivenes. And othrr problem is this device is not consisten with next pause and play reaction time. That's why I say It's not deliberatly done thay way by Sony. I feel It sonetimes struggles and needs more time.
4) Built quality is bad. I saw one person dropped it with case and he says even with the case devices edges are deformed considerably. It's not that obvious but It's there. The sheet metal is a thin indeed. And anodizing is really thin. I scratched the device quite easily. I can't tell you how thin the scratch is and how thin the anodizing.
Other general problem, In this time when people and many reviewers see aliminum or any kind of metal on portable device they will automatically say: very solid built quality. Many people said their edge of their A35 is going off the plastic top and bottom cover, production tolerances are bad. The sheet's thickness ane aliminum they use don't have enough toughness from that dropped photo.
I would say quality plastic with good coating ans smartphone class tolerances and without this super sharp edges (which will be the weakest point in case of impact) would be more appropriate design choice and lead considerably better built quality.
I don't recommend this device If you have options unlike me. Battery life is quite good If you don't use much of the effects and screen navigation. And compares to other Daps, battery life is really good as people here stated.
Extra: I didn't like IEMs. I tried and use A35 with low empedance headphones, all the time. May be they pair good witj spesifically IEMs, although I don't think so.