I honestly didn't notice that much of a change. Then again, it's hard to a/b it unless you had 2 units, one stock and one with the Mullards with both being fully warmed-up. That's the rub with an A/B comparison on the same WA8. You'd have to wait for it to warm-up after the swap. I certainly didn't experience the same shift as I have swapping tubes in other components. There was no "wow" moment. Off-topic, but I've been screwing around with how I feed the WA8. So, I've tried the following combos: 1.) Feed it directly from the Ultra-Rendu which is connected to a Sonic Transporter I5 (using it as the Roon Core). 2.) Feed it from my Yggy which is connected to the UR via the Sonic Transporter I5 (using it as the Roon Core), 3.) Go direct from my MacBook using Roon as the Core on my MacBook. 2.) has the most body which is initially very addicting, 1.) similar to 2.) but less body, 3.) Similar to 1.)'s body but more dynamic and immediate. Things seem way more open. This is obviously the least complicated and cheapest solution. Yup, good problem to have. It's also my favorite. Strangely, the top-end isn't as lit as 1 and 2. Has anyone else experienced similar?