Wow, yeah, that's pretty handy. I have to keep reminding myself that when a card says "any player" that does not exclude the player performing the action (like using harp or lyra to activate supertonic to activate another instrument).
I must be dim. How are you activating a given instrument more than once in a turn? Aren't they basically Powers?
instruments can only used once but songs can be used as many times as you have uses. she is saying use harp on inspiring supertonic to use lyra on supertonic to use another instrument. it's how AA get's a lot of his combos going
I listed the cards necessary for this in my response.
Instruments have powers, yeah, and I was activating each only once - it's just that the Harp and Lyra can both activate the Perform of a Harmony with their first action so I was including the name of the other one in brackets every time to try and illustrate this ;). Using both again at the end of the combo isn't actually using them again, but activating the second part of the text and thus finishing off using that instrument - using the first part to activate Suprtonic then interrupts the use of that instrument and it doesn't get to finish its text until everything that you chained off that first activation is done. You can activate Songs as many times as you like as they're not powers, but the Pipes specify that you need to activate two different Melodies so you would need both copies of Rhapsody/Sarabande out if you wanted to get double the effect.
You can, of course, use the first part of Supertonic's text to give someone else a power (someone like Greatest Legacy would be really good for this), and sometimes I do early on if I don't have the "Power Combo" out yet, but otherwise I prefer to trigger as many things as possible for myself and the rest of the chain tends to let other people do stuff anyway.
The Adept is really good with anyone who can let him use a power out of turn, and almost outright ridiculous if you're with Captain Cosmic and can get a Dynamic Siphon played on you - then every time the Siphon gets hit, Adept gets to use a power (ie kick off his entire power chain of whatever he can manage to string together). You can start deliberately plinking the Siphon with hero damage (I mean, other people on their turns can do this) to let the Adept do this pretty much every turn, and with at least one copy of Rhapsody out and something to activate it (even your base power) you can heal the Siphon right back up every time. And yes, I have done this - it was epic :D.
I got to give this a try last night, and it was very effective.
I also got Sarabande of Destruction out. It was novel to have such complete control over the environment. I think the Adept is likely to end up being one of my favorites. From reading about it I was expecting entirely the opposite.
The game also feels less fiddly the more I play it.
Yeah, sorry. Total reading fail on my part. I somehow read "finish off [instrument]" as "finish off with [instrument]" as in, "Play this instrument, then finish off with this instrument again." As I said, I may be dim. 
I find that I don't tend to get that many songs out before the game is over one way or the other.
The other thing that I can never get straight is whether or not both parts of one song can be played in the same round. I don't remember the exact instrument, but it allows you to play the Perform of a Harmony and the Accompany of a Harmony. Can those both be from the same card?
I know, rules forum. 
I really enjoy the Adept and am interested in getting more out of him. I don't find him fiddly, really, just overflowing with options and nuance.
All songs can be activated as many times as you want except for Melody's with Drake's Pipe because it specifies 2 different Melodys.
So if you were able to activate 2 Harmony Performs and 3 Harmony Accompanys you could activate all of them off the same Harmony.
I am sorry for being terse and not entirely informative (I listed the cards, but Ameena listed them first and described how to use them). I've only played Argent Adept twice so far, but both times I've had no shortage of perform and accompany options. It does take a bit to get set up, but if you can it is so totally worth it. Both times I've also had the card that let me search for an instrument which helped me, er, fine-tune Adept's performance.
Last couple of times I've played him, I managed to get out two or three songs and two or three instruments, which is enough to have a good effect on the game, but not enough to keep him from feeling locked into a particular role (usually healing when I've played him). Most of the time when he wasn't healing, he was feeding the Naturalist-Gator power uses. ;)
I find him a lot of fun, really. I need to get more plays in with him, but I often feel more incentive to take heroes I know better (Tempest, Tachyon, Sentinels) so we have a better chance of winning. We've finally beaten all but two villains now (Dreamer and V5), so maybe as we replay bad guys I'll branch out a little more.
You can do just fine on the Adept even with one instrument and a couple of songs. One thing to make sure of, at least, is that you get a song out during your first Play phase, otherwise your power is useless. I like to use Arcane Cadence during the early game, if I can get it (and chain it into other copies of itself if they come out - there are four in total and I have managed to chain all four of them in a row before now :D), to help speed up my setup. Later on I prefer Silver Shadow instead, ince I've got out some songs I can activate. It's also fine to lose an instrument every now and then if you need to (or reveal one during a Cadence but don't really want/need it right then) because you can get them back with Instrumental Conjuration which gives a free card draw on top of that :).
Adept is better in longer games when you have time to get properly set up, but he can do okay in shorter games too if you can get out evne one song that's good - let someone else draw a card or play one or something. Best three-hero team I can think of having played with was, in order of play, TLT, the Adept, and Unity. The first two let the third get set up enough to utterly destroy anything with many many bots, pretty much :D.
Of course, Polyphoric Flare is his best card.
Agreed! I personally enjoy the card art for it. I don't know why, but seeing Argent Adept to be so desperate to blast that dude is just amazing!
Well that through-the-back fired.
He's definitely onto something about the Role Playing aspect of it and how all the card effects work together to create a battle scene that makes sense in the context of the fight. The problem is that most people aren't really able to visualize the scene from the cards. Whether it's that they just don't think to do it or lack the imagination, I feel that those who compare Sentinels to "taxes" tend to only look at the numbers and nothing else.
When they make an attack, they see "+1 damage, +1 damage, +1 damage, -1 damage, damage type = fire."
When I make an attack, I see "Okay, so Tachyon is going in for a quick strike against Voss while Legacy yells "Charge!" in the background giving her even more motivation and a burst of energy. At the same time, Ra is channeling an aura of fire around everyone and Tachyon feels her fist glowing with the power of a firestorm. However, one of Voss's minions gets in Tachyon's way as she speeds towards him, causing her to stumble and lose some of her momentum. She hits Voss across the face and since they're fighting in the Phosphorescent Chamber in Atlantis, every hit feels like it has just that much more impact. Speeding into him, her fiery fist smacks into him and sends him flying across the room."
Of course, I also play other role-playing games, so it's easy for me to imagine how each scenario would play out. Remember the scene and how the environment effects a battle is just part of RPG's.
I'm not trying to mask the fiddliness of Sentinels. I think it definitely is a fiddly game. However, the fiddliness doesn't need to just be about the numbers. If you turn the fiddliness into a battle, it becomes one of the game's strengths, not a weakness.
I had to laugh a bit reading this:
http://steamcommunity.com/app/337150/discussions/0/611703999964826013/
Oh dear.
I'm always surprised when people feel the need to defend the game against being called fiddly. It is. It always has been. I use the word 'bitty' myself as you have to keep track (collectively) of all the little bits of information and the interactions between cards etc, and if that stops people enjoying the game, then that's OK. There are plenty of things that stop me enjoying certain games, it's all about preferences (neither of the two deck-builders I've played have felt terribly thematic for example)
With new players, I'm always up front about the cross-referencing, and then trying to limit the game to villains, heroes and environments where there isn't too much of it (beyond playing as Legacy to give the players a boost). If they get in to it, I can start stepping up the complexities as they get more apable of coping with it. The downside of this is despite having everything (bar most of the promos), I've got a lot of heroes I've never been able to use in person (or even see played) since a lot of my games have involved first time players
"bitty" just makes it sound adorable.