Completely opposite impressions. With u12t, Monarch 2, Softears Twilight, fostex th610, the se300 was definitely more digital sounding, with less refined, sharper notes. Also the layering was more flat, with weaker separation of plans in depth than on the sp1000. It was more like a flatter wall of sound. 4 other people shared the same impressions, including the owner of the audio shop who was more biased towards se300 wanting to sell it (one of the guys was an educated musician and an active sound engineer).
The sp1000 is more subtle, sweet, more analog and complex sounding. The se300 sounds rawer, more aggressive and energetic, which isnt a bad thing at all. It also has a very wide soundstage.
Great sounding device but overpriced imho. It should cost not more than the IBasso dx320 which is on the same level.