The thing with Blasters is they tend to use more endurance than the other ATs, due to having virtually no passives and lots of attacks. I would not recommend skipping Stamina unless you plan to heavily IO out your toon.
Siren's Song: the Sleep is already permanent without any slotting for Sleep, so you could just go heavily with Accuracy (it has 67.5% base, compared to 75% for most of your other attacks) and one Recharge. Unless you are taking Boost Range, a range enhancement could also work well here to give more depth to the cone.
Alternatively, 5 slots for "Call of the Sandman" gives great set bonuses as well as healthy +accuracy and +sleep. It's cheap too!
Defiant EU
Quaver: Kinetics/Sonic Defender
Semiquaver: Sonic/Kinetics Corruptor My Sonic/Elec skipped Stamina and doesn't have any of the unique +recovery IOs. Granted /Elec has Power Sink (which is superior to Conserve Power), but I think you could skip Stamina on Sonic/En with reasonable endred slotted on your attacks.
On the otherhand, I went stamina and skipped conserve completely... I don't like having to rely on a click power to give me my end back; I prefer a constant. It really comes to your personal choice.
As far as siren song, like Quaver said, just acc early on. Then one of the sleep sets: Sandman is great and usually cheap. Not sure what the market is up to lately, but the purple set for sleep (Fortunata? Don't remember) is one of the cheapest.
My Sonic/NRG was my first lvl 50, and I still love playing her years later. The synergy between the stunning effects in both sets is great for soloing. And honestly, I just love putting a spawn to sleep, walking right up to one mob and using power thrust, and shooting as he flies through the air. Total focus as the 'wake-up call' on the next, and a nice quick bonesmash/shout finisher for the third. Rinse, repeat. Heh.
And if you haven't noticed yet... use the 'bright' selection for sonic, and use two very strong and different colors (red/blue, teal/yellow) - the powers look AWESOME!
What they said. I tried skipping Stamina, but found it ultimately frustrating. It's probably something you could do, but it will be fiddly and require special slotting. I prefer to save Conserve Power for just before the nuke, which doesn't save anything on the nuke but makes everything after it cheaper.
The sleep IOs are pretty decent. Grab a set if there's a bonus you want, or frankenslot for acc/sleep/range/recharge. I don't mind having extra duration in sleep, as higher level enemies will wake up faster, and a heavily slotted Siren's Song lets you keep a lot of guys out of the fight (at least, on a defender). Also, if you go Call of the Sandman, consider making room for a chance to heal self proc. I don't use it on my defenders (dark and emp) because they have self-heals, but I use that proc on a mind/storm and find that it definitely helps. And, since Siren's Song does do minor damage, refreshing the sleep on a group isn't a complete waste of endurance.
Now I want to try a sonic/energy with Power Boost, Aid Self, and all the self-healing procs I can fit, just for the hell of it.
Virtue
Angel Witch II - Chord of Souls - Storm Witch II - Princess of the Dawn - Standing Horse - Witch of Xymox
Silent Scream - Shadow Witch II - Liquid Serenade - Nebulous Dawn - Ghost Witch II -Xiberia
Angel Witch II - Chord of Souls - Storm Witch II - Princess of the Dawn - Standing Horse - Witch of Xymox
Silent Scream - Shadow Witch II - Liquid Serenade - Nebulous Dawn - Ghost Witch II -Xiberia
This is great advice... thanks so much to all of you who have contributed! 
Satan trembles when he sees...
the weakest saint on his knees.
<----- Click there to learn how you can help!
Hello all,
Thanks to another thread's suggestion, I rolled up a Sonic/Energy Blaster... and I have to say... I am LOVING him... and his soloability.
I have a couple of questions and hope that anybody who has experience with either powerset can help.
1. Siren's Song... I'm thinking of slotting it: 2 rech/2 acc/2 sleep... is there a different slotting I should consider?
2. Conserve Energy... I like the power, but realize the recharge is painfully slow, so of course, I'll slot it 3 recharge. I'm just wondering... is the power, along with possibly slotting my powers with one endurance reducer each... able to have me skip stamina? Or should I not even consider skipping stamina if I want my guy to last the long run?
Thanks for any advice!
Satan trembles when he sees...
the weakest saint on his knees.