Just out of curiosity, how far can the Vali 2 go in terms of adequately driving headphones? I guess what I'm really asking is, has anyone found a set of cans that the Vali 2 couldn't keep up with? I'm definitely enjoying the Vali 2 with my HD650s (and other current headphones) and was wondering if I'm missing out on much compared to a Jotunheim or other higher end & more powerful amps.
I just found out that we will be getting a bonus this month at work and I'm doing my best not to get taken away by upgrade-itis again. I figured the Vali 2 is probably more than powerful enough except for some of the most bleeding edge cans, but I really don't have anything else to compare to right now. The HD650s are the most high end set of cans I've ever bought or listened to. Any input/advice would be appreciated!
I just got a Valhalla 2 because I needed to satisfy my curiousity about how an OTL amp drives Senns compared to a hybrid. I've only listened for a few hours, so my opinion may change over time, but the Vali 2 with a 6SN7 tube holds up very well against a stock Valhalla 2.
I have been doing some volume matched A/B testing (instant switching by splitting my DAC output, sending both headphone outs to a SYS, and using a RCA to 3.5 jack to plug my headphones into the output of the SYS). With HD6xx and HD580, both amps were easily distinguishable from a SMSL 793 II. Without knowing what the amps were ahead of time I had a 90%+ rate of liking the Vali and Valhalla over the SMSL.
Things got trickier between the Vali and the Valhalla. They definitely do sound different, but it would be hard to say one is strictly better than the other. I picked the Valhalla about 60% of the time and my wife chose the Vali at about the same rate. On some songs it was easier to hear a difference, but on others I had to make sure the switch was actually doing anything.
If I had to describe the difference, to me the Valhalla has a lower noise floor, creates more of a sense of space around instruments, and has slightly better bass extension. The Vali (with the 6SN7) was a little bit sharper in the treble and had a bit more impact in the mid bass. My wife enjoyed this slightly "fuller" sound, but I thought it sounded a bit more slow or congested. I can't comment on any of the longer term listening differences (e.g. is one more fatiguing over time) or what different tubes in the Valhalla might do to its sound. The differences were subtle, not night and day to me.
The rest of my system could be a bottleneck, but from a pure sound perspective the Vali (with a good tube) definitely holds it own and has some other advantages. It's more flexible with low impedance headphones, it's easier/cheaper to tube roll, is much smaller, runs a lot cooler, and costs half as much. I think for most people the Vali would be a better bang for the buck and some people would probably like it more irrespective of price.
That being said the Valhalla is a significantly more premium product in both look and feel. The volume knob alone is a huge improvement, and the Vali almost feels like a toy in comparison. The power section on the Valhalla is clearly better, the noise floor was lower for me, and it puts out more power into high impedance loads. I also seem to have a slight preference for its sound signature. For other people's systems and ears the differences may be more or less significant. Overall, it's still an impressive product at a competitive price.
My plan was to sell which ever I liked less (or the Valhalla if I couldn't tell the difference), but I think I may wind up keeping both and selling some other gear instead.