I am currently burning in a pair of Amperex Oracle Label ECC88's such as these:
So far the fit the sound signature you are looking for providing an abundance of detail with excellent separation and tight bass. I hope they develop a bit more soundstage depth and they'll be winners.
150+hrs on mine and they did not do. I found exactly the same. They are narrow in the soundstage. Warm, tight and they gots punch and kick. Fun tube but it leaves you wanting.