Yes, LCD2 is the most reliable from all the three, because it has less complicated driver design vs LCD3 and LCD4. IMHO LCD2 is the best headphone from Audeze from price/quality point of view. If I understand right, technology Audeze uses in their headphones can be precise in sound reproduction...

You are lucky. Search head-fi for driver issues with Audeze. The biggest problem, it can't be fixed. Only replacement possible. Cost of repair outside of warranty eg. for LCD3 around 800 usd. But sure, LCD has very nice design and though heavy still very comfortable to wear despite of very stiff...

Great all around source for its price mostly because of the light weight. Don't expect too much from functionality/connectivity options.

I don't know way to tell about modifications done without disassembly. Normally modification done with internal wiring and connectors, which as far as I know is not bad thing. Did you check that all the settings of the devices are exactly the same?

IMHO there no difference in SQ, but AK380 offers excellent compatible accessories range. Still best range on the market. As result it is very comfortable to use for any task you can imagine.

It not better, it is extremely versatile and very convenient to use. It is excellent DAC combo as do it all unit. Try it, you will love it. In SQ for easy to drive Sony headphones I didn't notice much difference compare to my TA-FA speaker amp. Hope it helps, ask more, if you have some specific...

There is very difficult to fight with Stax 009 in this price category (if you want versatile headphones).

Yes, you need an amplifier to enjoy the SQ 846 can offer.

Sony PHA3 provides great support for SE846. The only problem to mention are get hot and cable connectors to the source are not the best designed. Sound is excellent.

As portable version I would recommend any Sony PHA. PHA3 rocks, but get very hot.

Nope. You need an amplifier. 846 sounds way better connected using amplifier. Personally I use Sony PHA3. IMHO without amplifier SE215 is more reasonable option for IEMs.

True, Shure SE215 have very nice price / quality rate, relatively good SQ with excellent build quality for the price. You can get them as low as 70-80usd. Brand new from dealer goes around 150

Yes, it is relatively expensive, but it makes you life much easier like CD player vs playing CD from PC. AK Ripper MKii looks also great.

Nice enough amplifier for 009. Excellent connections to PC. Very hot in summer. Would call it reliable device. Were marginal problems in the beginning of use, but they disappeared itself. Probably some small assembly defects (some poor contacts, useless but nice dancing arrow stacked). Highly...

Unfortunately Audeze LCD3 and LCD4 drivers are unreliable. Unpleasant experience from Audeze headphones (LCD2,3,4). May be I believed marketing tricks and my expectations were too high. SQ is rather mediocre for each headphone price range. Personally moved to Sony and Stax. Life rocks again.