I ended up with many Channel 2 tone settings I really liked, but my number one was with the bass EQ nearly wide open, mid EQ around 3 o'clock, the treble backed off to around 4 o clock, and the ISF knob set to 12 o'clock, giving me plenty of cream on the sustain, but plenty of spank and crunch on the attack. Set this way, I found little reason to scoop out the mids. With everything set so hot, I was impressed with the amp's unobtrusive hiss levels. I kept the aforementioned Overdrive Voice switch off, as it did little for me that the knobs didn't give me with more precision. When engaged, the Overdrive Voice switch adds body and what Blackstar describes as a "smoother overdrive characteristic" by adding some mid-band gain. Maybe I'd be scooping out mids more with this feature engaged. I am used to a big bottom combo, which could explain why I kept the bass knob cranked.
The amp's Channel 2 Gain offers plenty of overdrive saturation at settings just above 12 o'clock. Sustain was everything you wanted at these levels—richly voiced and very live and uncompressed sounding and beautiful feedback was easy to attain and control—even with the gain pushed towards 3 o'clock. At higher gain levels finger and pick noise rose prominently, but was not unpleasing. In fact, it made the amp appear loud at practice volume levels.
EQ, Reverb and the Rest
Following the Channel 1 and 2 knobs are the previously mentioned treble, middle and bass equalization knobs. The EQ section only applies to the overdrive channel (channel 2). Depending on your music, pickups, and playing style, the tone requirements between clean and distortion can vary significantly and a separate EQ section for the clean channel would be 'nice to have.' However, if only one of the two channels on your amp is going to have EQ, it had better be the overdrive channel. I did not feel like I was missing out on EQ controls on channel 1, especially when set to Class A, thanks in large part to the HT Club 40's well-tuned cabinet. Again, the sealed back of this amp helps enormously in this regard via focus and upper mid definition. If you need more EQ for your clean tones, EQ stompboxes are common enough and will give you more control than the EQ section of most amps.
The last two knobs are what you'd expect—Reverb and Master Volume. When I listen to Jeff Beck on a song like “Blanket,” I think, “Wow, killer reverb.” When I dial in reverb on my own, or sometimes when I hear a guitarist use it in a club I think, “What's the deal with the reverb?” It's just so subjective in a live rock and roll environment. With that said, the HT Club 40's reverb is very reverb-y at high settings and less so at low settings. It's obviously digital, and while that's not a slam, if you're looking for a spring reverb, this amp doesn't have one. The Light/Dark switch on the back panel is a smart reverb parameter if you dig 'verb. Channel 1's Class A/B Voice with Reverb switched to Light provided gobs of shimmer without getting strident.
When was the last time you heard a 40 watt tube combo amp that wasn't hellah loud for its size? The Blackstar is no exception. It screams plenty loud for most clubs yet sounds great at mic-able levels so that you can get in the house mix. I think that is important since two sets of PA cabinets will do a far better job of saturating the venue space than a lone 12" in a sealed cabinet. There is plenty of headroom so that the Master Volume controls your level and not your tone, which is what all those other knobs are for.
The Final Mojo
The HT Club 40 is packed with tones. The versatility of the clean channel ranges from classic Pete Townshend to sparkly clean, uncolored guitar tones. Its overdrive channel ranges from British or American blues-rock (thanks to the ISF knob) to mega-aggressive distortion and anywhere in between, and even bits of both at the same time. I only wish it had an additional footswitch to go between Channel 1's Class A and Class A/B, which would essentially make this a powerful three-channel (tone-wise) amp. Though the Marshall-pedigreed company is based in the UK, the amp is manufactured in Korea. Even knowing that, its street price of $699 feels like a typo.
You predominantly play rock or metal guitar, need sensible, not
over-the-top versatility in a combo form.
You have a thing about Asian-made amps, you need the classic breakup of a
vintage tube amp, you expect onboard digital effects or modeling, or
play venues that require a stack instead of a combo.