Stanwal's suggestion regarding the room will not be eclipsed. More than ANY other component, the sound of the room will be what you hear when it's all said and done.
Ditto for what Tomcy6 said. I'll add that talking about an amplifier without the partnering loudspeaker leaves the equation unsolved. The partnership between the two goes a long way toward the sound being more engaging or relaxed.
That being said, NAD amps are more on the budget side of forward, and Krell (though not my cup of tea) on the other. If you're looking for a tube amplifier, consider the tube type/brand. For example, the Music Reference RM10 with EL84 is forward in the best of ways. Also, take a look at an OTL design.
Ditto for what Tomcy6 said. I'll add that talking about an amplifier without the partnering loudspeaker leaves the equation unsolved. The partnership between the two goes a long way toward the sound being more engaging or relaxed.
That being said, NAD amps are more on the budget side of forward, and Krell (though not my cup of tea) on the other. If you're looking for a tube amplifier, consider the tube type/brand. For example, the Music Reference RM10 with EL84 is forward in the best of ways. Also, take a look at an OTL design.