If you're looking for earbuds that delivers flawless performance across the board with a smooth and relaxed immersive signature, then look no further! Just make sure to pair it with a reference source with good power to get the best out of it.
If you're looking for an IEM that boasts one of the best soundstage at any price, features powerful, clean and quick bass with excellent control as well as a clear, open an articulate midrange and a well extended and engaging natural sounding treble then the FD5 is a no brainer! If you own a good copper cable I strongly suggest you plug it to the FD5 as it will be a more relaxed yet engaging listen and if you don't it's worth spending the extra money unless you enjoy a more energetic and brighter midrange. I would stick to the larger nozzle as the narrower brings most of the benefits a copper cable brings with the downside of making the soundstage smaller and penalizing the upper treble presence and the engaging lower treble.