A multi-stage control valve, comprising: a valve body; a seat ring disposed within the valve body and including: a first inner surface portion at least partially defining a generally cylindrical bore which extends through the seat ring along an axis; a plurality of flow passages (62, 64, 66) formed in the first inner surface portion to prescribed lengths in prescribed orientations relative to each other and extending in generally parallel relation to the axis of the bore, each of the flow passages (62, 64, 66) having a tortuous configuration defining a series of right angle turns, and including at least first sections which each extend in generally parallel relation to the axis of the bore and second sections which each extend generally circumferentially relative to the axis of the bore; and at least one flow control groove which is formed within the first inner surface portion and fluidly connects at least two of the flow passages (62, 64, 66) to each other, the multi-stage control valve being characterised by the at least two of the flow passages (62, 64, 66) having separate lowermost inflow ends and being connected via the at least one flow control groove; the multi-stage control valve further being characterised by comprising a valve plug advanced through the bore and reciprocally movable along the axis thereof in a manner which allows for selective variations in a portion of the length of at least one of the flow passages (62, 64, 66) covered thereby, by virtue of the lower portions of the flow passages progressively being uncovered by the retracting plug. a valve body; a seat ring disposed within the valve body and including: a first inner surface portion at least partially defining a generally cylindrical bore which extends through the seat ring along an axis; a plurality of flow passages (62, 64, 66) formed in the first inner surface portion to prescribed lengths in prescribed orientations relative to each other and extending in generally parallel relation to the axis of the bore, each of the flow passages (62, 64, 66) having a tortuous configuration defining a series of right angle turns, and including at least first sections which each extend in generally parallel relation to the axis of the bore and second sections which each extend generally circumferentially relative to the axis of the bore; and at least one flow control groove which is formed within the first inner surface portion and fluidly connects at least two of the flow passages (62, 64, 66) to each other, the multi-stage control valve being characterised by the at least two of the flow passages (62, 64, 66) having separate lowermost inflow ends and being connected via the at least one flow control groove; the multi-stage control valve further being characterised by comprising a valve plug advanced through the bore and reciprocally movable along the axis thereof in a manner which allows for selective variations in a portion of the length of at least one of the flow passages (62, 64, 66) covered thereby, by virtue of the lower portions of the flow passages progressively being uncovered by the retracting plug. a first inner surface portion at least partially defining a generally cylindrical bore which extends through the seat ring along an axis; a plurality of flow passages (62, 64, 66) formed in the first inner surface portion to prescribed lengths in prescribed orientations relative to each other and extending in generally parallel relation to the axis of the bore, each of the flow passages (62, 64, 66) having a tortuous configuration defining a series of right angle turns, and including at least first sections which each extend in generally parallel relation to the axis of the bore and second sections which each extend generally circumferentially relative to the axis of the bore; and at least one flow control groove which is formed within the first inner surface portion and fluidly connects at least two of the flow passages (62, 64, 66) to each other, the multi-stage control valve being characterised by the at least two of the flow passages (62, 64, 66) having separate lowermost inflow ends and being connected via the at least one flow control groove; the multi-stage control valve further being characterised by comprising a valve plug advanced through the bore and reciprocally movable along the axis thereof in a manner which allows for selective variations in a portion of the length of at least one of the flow passages (62, 64, 66) covered thereby, by virtue of the lower portions of the flow passages progressively being uncovered by the retracting plug.